Confirmation of an association between single nucleotide polymorphisms in the VDR gene with respiratory syncytial virus related disease in South African children

Vitamin D and viral infections: Infectious diseases, autoimmune diseases, and cancers

Viruses can cause many human diseases. Three types of human diseases caused by viruses are discussed in this chapter: infectious diseases, autoimmune diseases, and cancers. The infectious diseases included in this chapter include three respiratory tract diseases: influenza, COVID-19, and respiratory syncytial virus. In addition, the mosquito-borne dengue virus diseases are discussed. Vitamin D can reduce risk, severity, and mortality of the respiratory tract diseases and possibly for dengue virus. Many autoimmune diseases are initiated by the body's reaction to a viral infection. The protective role of vitamin D in Epstein-Barr virus-related diseases such as multiple sclerosis is discussed. There are a few cancers linked to viral infections. Such cancers include cervical cancer, head and neck cancers, Hodgkin's and non-Hodgkin's lymphoma, and liver cancer. Vitamin D plays an important role in reducing risk of cancer incidence and mortality, although not as strongly for viral-linked cancers as for other types of cancer.

Increased susceptibility to complicated pneumonia among egyptian children with FokI (rs2228570), not TaqI (rs731236), vitamin D receptor gene polymorphism in association with vitamin D deficiency: a case-control study

BACKGROUND

Determining a genetic contribution to the development of complicated community-acquired pneumonia in children may help understand underlying pathogenesis. We aimed to investigate the association between two vitamin D receptor (VDR) gene polymorphisms, FokI and TaqI, and susceptibility to complicated pneumonia in Egyptian children compared to uncomplicated pneumonia. Associations with 25 hydroxy-vitamin D serum level were studied.

METHODS

This was a case-control study that included 320 participants divided into 2 groups: patients and controls. The patients' group included 100 children hospitalized with complicated pneumonia and 100 with uncomplicated pneumonia. 120 age and sex-matched apparently healthy children served as controls. The VDR FokI and TaqI polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. 25 hydroxy-vitamin D level was estimated in serum using ELISA.

RESULTS

Regarding FokI, homozygous CC genotype was more common in complicated (52%) than uncomplicated pneumonia (28%) and controls (10%) (OR = 65; 95%CI (5.13-822.63), p < 0.001) and (OR = 4.3; 95%CI (0.7-27.16), p = 0.003), respectively. Children carrying C allele possessed 3 higher odds for complicated than uncomplicated pneumonia (OR = 3.08; 95%CI (1.33-7.14), p < 0.001). Heterozygous CT genotype increased susceptibility to complicated pneumonia (OR = 13.7; 95%CI (4.6-40.1), p < 0.001), not uncomplicated pneumonia (OR = 1.56; 95%CI (0.86-2.85), p = 0.145). Among complicated pneumonia, vitamin D level was lower in CC (6.92 ± 2.6ng/ml) than CT (9.55 ± 3.2 ng/ml) and TT genotype carriers (13.13 ± 3.6ng/ml) (p < 0.001). There was no significant difference between patients and controls as regards TaqI genotypes and alleles.

CONCLUSION

In association with vitamin D deficiency, VDR gene FokI polymorphism, not TaqI, is a genetic risk factor for complicated pneumonia in Egyptian children.

Plasma 25-Hydroxyvitamin D Level and VDR Gene Single Nucleotide Polymorphism rs2228570 Influence on COVID-19 Susceptibility among the Kazakh Ethnic Group-A Pilot Study

Low plasma levels of the vitamin D metabolite 25-hydroxyvitamin D [25(OH)D] and the vitamin D receptor (VDR) gene single nucleotide polymorphisms (SNPs) have been associated with the body's susceptibility to infectious diseases, including COVID-19. In this pilot retrospective study, representatives of the Kazakh population (central Kazakhstan) were divided into groups based on the test for IgM and IgG for coronavirus infection. We compared the 25(OH)D plasma levels and concluded that the COVID-19-positive group values (25.17 ng/mL ± 16.65) were statistically lower (p = 0.0114) compared to the COVID-19-negative ones (35.58 ng/mL ± 20.67). There was no association between age, gender and 25(OH)D concentration within the groups (p > 0.05). The genotyping of rs2228570 was performed using a TaqMan Real-Time PCR assay. Allele C predominated among the COVID-19-negative participants and significantly reduced the likelihood of coronavirus infection (p < 0.0001; OR = 0.0804; 95% CI 0.02357-0.2798). There were no statistically significant differences in the frequencies of the A, G and T alleles in the studied groups (p > 0.05). The GG genotype of rs2228570 was associated with a 4.131-fold increased likelihood of COVID-19 infection (p = 0.0288; χ2 = 5.364; OR = 4.131; 95% CI 1.223-13.71). Comprehensive studies are required to determine whether low 25(OH)D plasma concentrations and genetic background represent a risk factor for COVID-19 infection.

Vitamin D deficiency and vitamin D receptor FokI polymorphism as risk factors for COVID-19

BACKGROUND

Given the sparse data on vitamin D status in pediatric COVID-19, we investigated whether vitamin D deficiency could be a risk factor for susceptibility to COVID-19 in Egyptian children and adolescents. We also investigated whether vitamin D receptor (VDR) FokI polymorphism could be a genetic marker for COVID-19 susceptibility.

METHODS

One hundred and eighty patients diagnosed to have COVID-19 and 200 matched control children and adolescents were recruited. Patients were laboratory confirmed as SARS-CoV-2 positive by real-time RT-PCR. All participants were genotyped for VDR Fok1 polymorphism by RT-PCR. Vitamin D status was defined as sufficient for serum 25(OH) D at least 30 ng/mL, insufficient at 21-29 ng/mL, deficient at <20 ng/mL.

RESULTS

Ninety-four patients (52%) had low vitamin D levels with 74 (41%) being deficient and 20 (11%) had vitamin D insufficiency. Vitamin D deficiency was associated with 2.6-fold increased risk for COVID-19 (OR = 2.6; [95% CI 1.96-4.9]; P = 0.002. The FokI FF genotype was significantly more represented in patients compared to control group (OR = 4.05; [95% CI: 1.95-8.55]; P < 0.001).

CONCLUSIONS

Vitamin D deficiency and VDR Fok I polymorphism may constitute independent risk factors for susceptibility to COVID-19 in Egyptian children and adolescents.

IMPACT

Vitamin D deficiency could be a modifiable risk factor for COVID-19 in children and adolescents because of its immune-modulatory action. To our knowledge, ours is the first such study to investigate the VDR Fok I polymorphism in Caucasian children and adolescents with COVID-19. Vitamin D deficiency and the VDR Fok I polymorphism may constitute independent risk factors for susceptibility to COVID-19 in Egyptian children and adolescents. Clinical trials should be urgently conducted to test for causality and to evaluate the efficacy of vitamin D supplementation for prophylaxis and treatment of COVID-19 taking into account the VDR polymorphisms.

Association of ApaI rs7975232 and BsmI rs1544410 in clinical outcomes of COVID-19 patients according to different SARS-CoV-2 variants

A growing body of research has shown how important vitamin D is in the prognosis of coronavirus disease 19 (COVID-19). The vitamin D receptor is necessary for vitamin D to perform its effects, and its polymorphisms can help in this regard. Therefore, we aimed to evaluate whether the association of ApaI rs7975232 and BsmI rs1544410 polymorphisms in different severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants were influential in the outcomes of COVID-19. The polymerase chain reaction-restriction fragment length polymorphism method was utilized to determine the different genotypes of ApaI rs7975232 and BsmI rs1544410 in 1734 and 1450 patients who had recovered and deceased, respectively. Our finding revealed that the ApaI rs7975232 AA genotype in the Delta and Omicron BA.5 and the CA genotype in the Delta and Alpha variants were associated with higher mortality rate. Also, the BsmI rs1544410 GG genotype in the Delta and Omicron BA.5 and the GA genotype in the Delta and Alpha variants were related to a higher mortality rate. The A-G haplotype was linked with COVID-19 mortality in both the Alpha and Delta variants. The A-A haplotype for the Omicron BA.5 variants was statistically significant. In conclusion, our research revealed a connection between SARS-CoV-2 variants and the impacts of ApaI rs7975232 and BsmI rs1544410 polymorphisms. However, more research is still needed to substantiate our findings.

The relationship between 896A/G (rs4986790) polymorphism of TLR4 and infectious diseases: A meta-analysis

Toll-like Receptors (TLRs), such as the TLR4, are genes encoding transmembrane receptors of the same name, which induce a pro- or anti-inflammatory response according to their expression as the host's first line of defense against pathogens, such as infectious ones. Single nucleotide polymorphisms (SNPs) are the most common type of mutation in the human genome and can generate functional modification in genes. The aim of this article is to review in which infectious diseases there is an association of susceptibility or protection by the TLR4 SNP rs4986790. A systematic review and meta-analysis of the literature was conducted in the Science Direct, PUBMED, MEDLINE, and SciELO databases between 2011 and 2021 based on the dominant genotypic model of this SNP for general and subgroup analysis of infectious agent type in random effect. Summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated for genotypic comparison. I² statistics were calculated to assess the presence of heterogeneity between studies and funnel plots were inspected for indication of publication bias. A total of 27 articles were included, all in English. Among the results achieved, the categories of diseases that were most associated with the SNP studied were in decreasing order of number of articles: infections by bacteria (29.63%); caused by viruses (22.23%); urinary tract infection-UTI (7.4%), while 11 studies (40.74%) demonstrated a nonsignificant association. In this meta-analysis, a total of 5599 cases and 5871 controls were finalized. The present meta-analysis suggests that there is no significant association between TLR4-rs4986790 SNP and infections (OR = 1,11; 95% CI: 0,75-1,66; p = 0,59), but in the virus subgroup it was associated with a higher risk (OR = 2,16; 95% CI: 1,09-4,30; p = 0,03). The subgroups of bacteria and parasites did not show statistical significance (OR = 0,86; 95% CI: 0,56-1,30; p = 0,47, and no estimate of effects, respectively). Therefore, it has been shown that a diversity of infectious diseases is related to this polymorphism, either by susceptibility or even severity to them, and the receptor generated is also crucial for the generation of cell signaling pathways and immune response against pathogens.

Impact of genetic polymorphisms related to innate immune response on respiratory syncytial virus infection in children

Respiratory syncytial virus (RSV) causes lower respiratory tract infections and bronchiolitis, mainly affecting children under 2 years of age and immunocompromised patients. Currently, there are no available vaccines or efficient pharmacological treatments against RSV. In recent years, tremendous efforts have been directed to understand the pathological mechanisms of the disease and generate a vaccine against RSV. Although RSV is highly infectious, not all the patients who get infected develop bronchiolitis and severe disease. Through various sequencing studies, single nucleotide polymorphisms (SNPs) have been discovered in diverse receptors, cytokines, and transcriptional regulators with crucial role in the activation of the innate immune response, which is implicated in the susceptibility to develop or protect from severe forms of the infection. In this review, we highlighted how variations in the key genes affect the development of innate immune response against RSV. This data would provide crucial information about the mechanisms of viral infection, and in the future, could help in generation of new strategies for vaccine development or generation of the pharmacological treatments.

Interindividual immunogenic variants: Susceptibility to coronavirus, respiratory syncytial virus and influenza virus

The coronavirus disease (Covid-19) pandemic is the most serious event of the year 2020, causing considerable global morbidity and mortality. The goal of this review is to provide a comprehensive summary of reported associations between inter-individual immunogenic variants and disease susceptibility or symptoms caused by the coronavirus strains severe acute respiratory syndrome-associated coronavirus, severe acute respiratory syndrome-associated coronavirus-2, and two of the main respiratory viruses, respiratory syncytial virus and influenza virus. The results suggest that the genetic background of the host could affect the levels of proinflammatory and anti-inflammatory cytokines and might modulate the progression of Covid-19 in affected patients. Notably, genetic variations in innate immune components such as toll-like receptors and mannose-binding lectin 2 play critical roles in the ability of the immune system to recognize coronavirus and initiate an early immune response to clear the virus and prevent the development of severe symptoms. This review provides promising clues related to the potential benefits of using immunotherapy and immune modulation for respiratory infectious disease treatment in a personalized manner.

A mouse model of human TLR4 D299G/T399I SNPs reveals mechanisms of altered LPS and pathogen responses

Two cosegregating single-nucleotide polymorphisms (SNPs) in human TLR4, an A896G transition at SNP rs4986790 (D299G) and a C1196T transition at SNP rs4986791 (T399I), have been associated with LPS hyporesponsiveness and differential susceptibility to many infectious or inflammatory diseases. However, many studies failed to confirm these associations, and transfection experiments resulted in conflicting conclusions about the impact of these SNPs on TLR4 signaling. Using advanced protein modeling from crystallographic data of human and murine TLR4, we identified homologous substitutions of these SNPs in murine Tlr4, engineered a knock-in strain expressing the D298G and N397I TLR4 SNPs homozygously, and characterized in vivo and in vitro responses to TLR4 ligands and infections in which TLR4 is implicated. Our data provide new insights into cellular and molecular mechanisms by which these SNPs decrease the TLR4 signaling efficiency and offer an experimental approach to confirm or refute human data possibly confounded by variables unrelated to the direct effects of the SNPs on TLR4 functionality.

Hidden in plain sight: The effects of BCG vaccination in the COVID-19 pandemic

To investigate the relationship between Bacille Calmette‐Guérin (BCG) vaccination and SARS‐CoV‐2 by a bioinformatics approach, two datasets for the SARS‐CoV‐2 infection group and BCG‐vaccinated group were downloaded. Differentially Expressed Genes were identified. Gene ontology and pathways were functionally enriched, and networking was constructed in NetworkAnalyst. Lastly, the correlation between post‐BCG vaccination and COVID‐19 transcriptome signatures was established. A total of 161 DEGs (113 upregulated DEGs and 48 downregulated genes) were identified in the SARS‐CoV‐2 group. In the pathway enrichment analysis, a cross‐reference of upregulated Kyoto Encyclopedia of Genes and Genomes pathways in SARS‐CoV‐2 with downregulated counterparts in the BCG‐vaccinated group, resulted in the intersection of 45 common pathways, accounting for 86.5% of SARS‐CoV‐2 upregulated pathways. Of these intersecting pathways, a vast majority were immune and inflammatory pathways with top significance in interleukin‐17, tumor necrosis factor, NOD‐like receptors, and nuclear factor‐κB signaling pathways. Given the inverse relationship of the specific differentially expressed gene pathways highlighted in our results, the BCG‐vaccine may play a protective role against COVID‐19 by mounting a nonspecific immunological response and further investigation of this relationship is warranted.

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).

Effects of host genetic variations on response to, susceptibility and severity of respiratory infections

The recent outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a global crisis, necessitating the identification of genetic factors that modulate the risk of disorder or its severity. The current data about the role of genetic risk factors in determination of rate of SARS-CoV-2 infection in each ethnic group and the severity of disorder is limited. Moreover, several confounding parameters such as the number of tests performed in each country, the structure of the population especially the age distribution, the presence of risk factors for respiratory disorders such as smoking and other environmental factors might be involved in the variability in disease course or prevalence of infection among different ethnic groups. However, assessment of the role of genetic variants in determination of the course of other respiratory infections might help in recognition of possible candidate for further analysis in patients affected with SARS-CoV-2. In the current review, we summarize the data showing the association between genomic variants and risk of acute respiratory distress syndrome, respiratory infections or severity of these conditions with an especial focus on the SARS-CoV-2.

Association of chronic inflammation and accelerated atherosclerosis among an indigenous black population with chronic kidney disease

Introduction

Inflammation plays a major role in the development of atherosclerosis and cardiovascular morbidity and mortality in chronic kidney disease (CKD) patients. Toll-like receptor-4 (TLR4) is a major receptor for lipopolysaccharides (endotoxin) and other ligands involved in the pathogenesis of inflammation. We determined whether endotoxin levels and the presence of TLR4 polymorphisms are associated with markers of inflammation and atherosclerosis among South African CKD patients.

Materials and methods

Endotoxin, lipopolysaccharide binding protein (LBP), serum CD14 (sCD14), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1) and carotid intima media thickness (CIMT) were measured in 160 participants (120 CKD patients and 40 controls). Associations between endotoxins and CIMT in the presence of sCD14, IL-8 and MCP-1, were assessed using odds ratios. Participants were screened for the presence of Asp299Gly and Thr399Ile TLR4 polymorphisms, and CIMT and inflammatory markers were compared between subjects with and without TLR4 polymorphisms.

Results

Endotoxin levels correlated with sCD14 (r = 0.441, p<0.001) and MCP-1 (r = 0.388, p<0.001) levels while increased CIMT was associated with MCP-1 (r = 0.448, p<0.001), sCD14 levels (r = 0.476, p<0.001), LBP (r = 0.340, p<0.001), and IL-8 (r = 0.395, p<0.001). Atherosclerosis was associated with endotoxin levels (odds ratio: 4.95; 95% confidence interval: 2.52–9.73; p<0.001), and was predicted by higher serum levels of inflammatory markers. Analysis of patients with TLR4 polymorphisms showed reduced serum levels of inflammatory markers and CIMT values compared with the patients carrying the wild type TLR4 alleles.

Conclusion

The study demonstrated associations between circulating endotoxaemia, systemic inflammation and accelerated atherosclerosis among South African CKD patients, and showed that the atherogenic predictive power of endotoxaemia was significantly increased by the presence of elevated levels of inflammatory markers. Additional findings, which must be confirmed, suggest that TLR4 polymorphisms are associated with low levels of inflammatory markers and CIMT values.

The interplay between vitamin D and viral infections

The pleiotropic role of vitamin D has been explored over the past decades and there is compelling evidence for an epidemiological association between poor vitamin D status and a variety of diseases. While the potential anti-viral effect of vitamin D has recently been described, the underlying mechanisms by which vitamin D deficiency could contribute to viral disease development remain poorly understood. The possible interactions between viral infections and vitamin D appear to be more complex than previously thought. Recent findings indicate a complex interplay between viral infections and vitamin D, including the induction of anti-viral state, functional immunoregulatory features, interaction with cellular and viral factors, induction of autophagy and apoptosis, and genetic and epigenetic alterations. While crosstalk between vitamin D and intracellular signalling pathways may provide an essential modulatory effect on viral gene transcription, the immunomodulatory effect of vitamin D on viral infections appears to be transient. The interplay between viral infections and vitamin D remains an intriguing concept, and the global imprint that vitamin D can have on the immune signature in the context of viral infections is an area of growing interest.

DC-SIGN and VDR polymorphisms are associated with chronic form of paracoccidioidomycosis with oral manifestations

Paracoccidioidomycosis (PCM) is a granulomatous disease caused by fungi of the species complex of the Paracoccidioides genus. One of the main clinical manifestations of PCM is the presence of oral lesions with the presence of epithelioid granulomas. In this work, we aimed to evaluate the frequency of SNPs in the TNF-α, JAK1, VDR, DC-SIGN and FcγRIIa genes in patients with chronic PCM and verify possible association of these SNPs with the organisation pattern of the granulomas in the oral lesions. A total of 66 samples of DNA were obtained from oral lesions biopsies and 106 DNA samples were obtained from healthy individuals. The individuals were genotyped for SNPs in DC-SIGN (rs4804803), FcγRIIa (rs1801274), JAK1 (rs11208534), TNF-α (rs1800629) and VDR (rs7975232) by real-time PCR and allele discrimination method. Granulomas were classified as loose or dense according to the histological pattern. In the VDR (rs7975232), the CC genotype (P < 0.001, OR = 5.94, 95% CI = 2.07-17.05), and the C allele (P = 0.027, OR = 2.71, 95% CI = 1.07-6.86), as well as the GG genotype in DC-SIGN (rs4804803) (P = 0.032, OR: 3.76, 95%, I = 1.06-13.38) are associated with an increased risk of oral PCM. Our data indicate that VDR and DC-SIGN genetics variations are related to the susceptibility of oral PCM in the group of patients analysed.

Association of vitamin D receptor gene FokI polymorphism and susceptibility to CAP in Egyptian children: a multicenter study

BACKGROUND

Community-acquired pneumonia (CAP) is the leading cause of child deaths around the world. Recently, the vitamin D receptor (VDR) gene has emerged as a susceptibility gene for CAP.

OBJECTIVES

To evaluate the association of the VDR gene Fok I polymorphism with susceptibility to CAP in Egyptian children.

METHODS

This was a multicenter case-control study of 300 patients diagnosed with CAP, and 300 well-matched healthy control children. The VDR Fok I (rs2228570) polymorphism was genotyped by PCR-restriction fragment length polymorphism (RFLP), meanwhile serum 25-hydroxy vitamin D (25D) level was assessed using ELISA method.

RESULTS

The frequencies of the VDR FF genotype and F allele were more common in patients with CAP than in our control group (OR = 3.6; (95% CI: 1.9-6.7) for the FF genotype; P = 0.001) and (OR: 1.8; (95% CI: 1.4-2.3) for the F allele; P = 0.01). Patients carrying the VDR FF genotype had lower serum (25D) level (mean; 14.8 ± 3.6 ng/ml) than Ff genotype (20.6 ± 4.5 ng/ml) and the ff genotype (24.5 ± 3.7 ng/ml); P < 0.01.

CONCLUSION

The VDR gene Fok I (rs2228570) polymorphism confers susceptibility to CAP in Egyptian children.

Inter-individual variation in health and disease associated with pulmonary infectious agents

Respiratory infectious diseases resulting from bacterial or viral pathogens such as Mycobacterium tuberculosis, Streptococcus pneumoniae, respiratory syncytial virus (RSV), or influenza, are major global public health concerns. Lower respiratory tract infections are leading causes of morbidity and mortality, only behind ischemic heart disease and stroke (GBD 2015 LRI Collaborators in Lancet Infect Dis 17(11):1133–1161, 2017). Developing countries are particularly impacted by these diseases. However, while many are infected with viruses such as RSV (> 90% of all individuals are infected by age 2), only sub-populations develop severe disease. Many factors may contribute to the inter-individual variation in response to respiratory infections, including gender, age, socioeconomic status, nutrition, and genetic background. Association studies with functional single nucleotide polymorphisms in biologically plausible gene candidates have been performed in human populations to provide insight to the molecular genetic contribution to pulmonary infections and disease severity. In vitro cell models and genome-wide association studies in animal models of genetic susceptibility to respiratory infections have also identified novel candidate susceptibility genes, some of which have also been found to contribute to disease susceptibility in human populations. Genetic background may also contribute to differential efficacy of vaccines against respiratory infections. Development of new genetic mouse models such as the collaborative cross and diversity outbred mice should provide additional insight to the mechanisms of genetic susceptibility to respiratory infections. Continued investigation of susceptibility factors should provide insight to novel strategies to prevent and treat disease that contributes to global morbidity and mortality attributed to respiratory infections.

Vitamin D receptor genotype influences risk of upper respiratory infection

SNP in the vitamin D receptor (VDR) gene is associated with risk of lower respiratory infections. The influence of genetic variation in the vitamin D pathway resulting in susceptibility to upper respiratory infections (URI) has not been investigated. We evaluated the influence of thirty-three SNP in eleven vitamin D pathway genes (DBP, DHCR7, RXRA, CYP2R1, CYP27B1, CYP24A1, CYP3A4, CYP27A1, LRP2, CUBN and VDR) resulting in URI risk in 725 adults in London, UK, using an additive model with adjustment for potential confounders and correction for multiple comparisons. Significant associations in this cohort were investigated in a validation cohort of 737 children in Manchester, UK. In all, three SNP in VDR (rs4334089, rs11568820 and rs7970314) and one SNP in CYP3A4 (rs2740574) were associated with risk of URI in the discovery cohort after adjusting for potential confounders and correcting for multiple comparisons (adjusted incidence rate ratio per additional minor allele ≥1·15, P for trend ≤0·030). This association was replicated for rs4334089 in the validation cohort (P for trend=0·048) but not for rs11568820, rs7970314 or rs2740574. Carriage of the minor allele of the rs4334089 SNP in VDR was associated with increased susceptibility to URI in children and adult cohorts in the United Kingdom.

Vitamin D Receptor polymorphisms and risk of enveloped virus infection: A meta-analysis

INTRODUCTION

Vitamin-D plays a role regulating the immune response against to viral infection. In this sense, vitamin-D deficiency may confer increased susceptibility to enveloped virus infection such as HIV, Hepatitis, Dengue and Respiratory Syncytial virus infection, among others. Vitamin D activity is mediated by its receptor (VDR), which acts as a transcription factor modulating the expression of genes triggering the response against viruses. To date, six major VDR polymorphisms (Cdx, A1012G, FokI, BsmI, ApaI and TaqI) have been studied in the context of viral infection susceptibility. Reported studies show controversial results probably due to statistical lack of power and population genetic differences.

AIMS

To do a systematic review of the published data and to perform a meta-analysis examining the role of six VDR polymorphisms on infection susceptibility to enveloped virus.

RESULTS

From all markers and virus considered an association of FokI polymorphism with RSV infection emerges as significant. The worldwide distribution of risk T-allele reveals a lower prevalence in African populations that runs parallel with the relative lower incidence of RSV-associated severe ALRI in children <1 year described in African samples.

CONCLUSION

The results disclose FokI polymorphism as a relevant variant capturing the association of VDR polymorphisms with viral infection.

Association between single nucleotide polymorphisms in TLR4, TLR2, TLR9, VDR, NOS2 and CCL5 genes with acute viral bronchiolitis

Background

Acute viral bronchiolitis is the leading cause of hospitalization among infants during the first year of life. Most infants hospitalized for bronchiolitis do not present risk factors and are otherwise healthy. Our objective was to determine the genetic features associated with the risk and a severe course of bronchiolitis.

Methods

We prospectively evaluated 181 infants with severe bronchiolitis admitted at three hospitals over a 2-year period, who required oxygen therapy. The control group consisted of 536 healthy adults. Patients were evaluated for the presence of comorbidities (premature birth, chronic respiratory disease, and congenital heart disease), underwent nasopharyngeal aspirate testing for virus detection by multiplex-PCR, and SNPs identification in immune response genes. Patient outcomes were assessed.

Results

We observed association between SNP rs2107538*CCL5 and bronchiolitis caused by respiratory syncytial virus(RSV) and RSV-subtype-A, and between rs1060826*NOS2 and bronchiolitis caused by rhinovirus. SNPs rs4986790*TLR4, rs1898830*TLR2, and rs2228570*VDR were associated with progression to death. SNP rs7656411*TLR2 was associated with length of oxygen use; SNPs rs352162*TLR9, rs187084*TLR9, and rs2280788*CCL5 were associated with requirement for intensive care unit admission; while SNPs rs1927911*TLR4, rs352162*TLR9, and rs2107538*CCL5 were associated with the need for mechanical ventilation.

Conclusions

Our findings provide some evidence that SNPs in CCL5 and NOS2 are associated with presence of bronchiolitis and SNPs in TLR4, TLR2, TLR9, VDR and CCL5 are associated with severity of bronchiolitis.

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SNPs in CCL5 and NOS2 genes are associated with presence of bronchiolitis.

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SNPs in TLR4, TLR2 and TLR9, genes are associated with severity of bronchiolitis.

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SNPs in VDR and CCL5 genes are associated with severity of bronchiolitis.

Human Genetic Determinants of Viral Diseases

Much progress has been made in the identification of specific human gene variants that contribute to enhanced susceptibility or resistance to viral diseases. Herein we review multiple discoveries made with genome-wide or candidate gene approaches that have revealed significant insights into virus-host interactions. Genetic factors that have been identified include genes encoding virus receptors, receptor-modifying enzymes, and a wide variety of innate and adaptive immunity-related proteins. We discuss a range of pathogenic viruses, including influenza virus, respiratory syncytial virus, human immunodeficiency virus, human T cell leukemia virus, human papilloma virus, hepatitis B and C viruses, herpes simplex virus, norovirus, rotavirus, parvovirus, and Epstein-Barr virus. Understanding the genetic underpinnings that affect infectious disease outcomes should allow tailored treatment and prevention approaches in the future.

Role of vitamin D in cystic fibrosis and non-cystic fibrosis bronchiectasis

Bronchiectasis is usually classified as cystic fibrosis (CF) related or CF unrelated (non-CF); the latter is not considered an orphan disease any more, even in developed countries. Irrespective of the underlying etiology, bronchiectasis is the result of interaction between host, pathogens, and environment. Vitamin D is known to be involved in a wide spectrum of significant immunomodulatory effects such as down-regulation of pro-inflammatory cytokines and chemokines. Respiratory epithelial cells constitutively express 1α-hydroxylase leading to the local transformation of the inactive 25(OH)-vitamin D to the active 1,25(OH)₂-vitamin D. The latter through its autocrine and paracrine functions up-regulates vitamin D dependent genes with important consequences in the local immunity of lungs. Despite the scarcity of direct evidence on the involvement of vitamin D deficiency states in the development of bronchiectasis in either CF or non-CF patients, it is reasonable to postulate that vitamin D may play some role in the pathogenesis of lung diseases and especially bronchiectasis. The potential contribution of vitamin D deficiency in the process of bronchiectasis is of particular clinical importance, taking into consideration the increasing prevalence of vitamin D deficiency worldwide and the significant morbidity of bronchiectasis. Given the well-established association of vitamin D deficiency with increased inflammation, and the indicative evidence for harmful consequences in lungs, it is intriguing to speculate that the administration of vitamin D supplementation could be a reasonable and cost effective supplementary therapeutic approach for children with non-CF bronchiectasis. Regarding CF patients, maybe in the future as more data become available, we have to re-evaluate our policy on the most appropriate dosage scheme for vitamin D.

Respiratory syncytial virus-Host interaction in the pathogenesis of bronchiolitis and its impact on respiratory morbidity in later life

Respiratory syncytial virus (RSV) is the most common agent of severe airway disease in infants and young children. Large epidemiologic studies have demonstrated a clear relationship between RSV infection and subsequent recurrent wheezing and asthma into childhood, thought to be predominantly related to long-term changes in neuroimmune control of airway tone rather than to allergic sensitization. These changes appear to be governed by the severity of the first RSV infection in infancy which in term depends on viral characteristics and load, but perhaps as importantly, on the genetic susceptibility and on the constitutional characteristic of the host. A variety of viral and host factors and their interplay modify the efficiency of the response to infection, including viral replication and the magnitude of structural and functional damage to the respiratory structures, and ultimately the extent, severity, and duration of subsequent wheezing.

Vitamin D (FokI) Receptor Gene Polymorphism is associated with Vitamin D Deficiency and Chronic Musculoskeletal Pain. A meta-analysis

Background: Musculoskeletal pain is the most common chronic pain experienced by older adults. The aim of this study is to explore the associations between vitamin D (FOKI) receptor gene polymorphism (VDR) and vitamin D deficiency (VDD) and chronic musculoskeletal pain. Methods: Cross-sectional studies published in English from January 2000 to January 2015which reported prevalence of chronic pain (CP) and chronic musculoskeletal pain (CMP) were included in this systematic review and meta-analysis. A heat map was used to visualize and observe the correlation between VDR and CMP, CP and VDD. Results: 20 studies (N = 216,365) were included in the analysis, which showed an overall pooled prevalence estimate of CMP and CP as 30.6 per 100 (95 % CI: 30.59, 30.69) and 27.9 per 100 (95 % CI: 27.68, 28.24) respectively. The heat map clustering analysis visualizes the similarity between CP and CMP. Moreover, a direct correlation was observed between the three disease conditions (namely CMP, CP, and VDD) and FokI VDR polymorphism (FF). Spearman's correlation analyses with adjusted r² revealed that there is a statistically significant interaction effect of the FF genotype and VDD on CMP (r² = 0.19, p = 0.03), a marginally significant interaction effect of the ff genotype and VDD on CMP (r² = 0.11, p = 0.08). VDD was also associated with increased CMP (r² = 0.19, p = 0.028). The pooled estimates of the prevalence of CMP in this review were found to be high. Conclusion: FokI VDR gene polymorphism (FF) plays an important role in the relationship between VDD and CMP.

Single nucleotide polymorphisms in the vitamin D pathway associating with circulating concentrations of vitamin D metabolites and non-skeletal health outcomes: Review of genetic association studies

Polymorphisms in genes encoding proteins involved in vitamin D metabolism and transport are recognised to influence vitamin D status. Syntheses of genetic association studies linking these variants to non-skeletal health outcomes are lacking. We therefore conducted a literature review to identify reports of statistically significant associations between single nucleotide polymorphisms (SNP) in 11 vitamin D pathway genes (DHCR7, CYP2R1, CYP3A4, CYP27A1, DBP, LRP2, CUB, CYP27B1, CYP24A1, VDR and RXRA) and non-bone health outcomes and circulating levels of 25-hydroxyvitamin D (25[OH]D and 1,25-dihydroxyvitamin D (1,25[OH]₂D). A total of 120 genetic association studies reported positive associations, of which 44 investigated determinants of circulating 25(OH)D and/or 1,25(OH)₂D concentrations, and 76 investigated determinants of non-skeletal health outcomes. Statistically significant associations were reported for a total of 55 SNP in the 11 genes investigated. There was limited overlap between genetic determinants of vitamin D status and those associated with non-skeletal health outcomes: polymorphisms in DBP, CYP2R1 and DHCR7 were the most frequent to be reported to associate with circulating concentrations of 25(OH)D, while polymorphisms in VDR were most commonly reported to associate with non-skeletal health outcomes, among which infectious and autoimmune diseases were the most represented.

Vitamin D Status and Its Consequences for Health in South Africa

In this review, reports were retrieved in which vitamin D status, as assessed by serum 25-hydroxyvitamin D [25(OH)D] levels, was measured in South African population groups with varied skin colours and ethnicities. Healthy children and adults were generally vitamin D-sufficient [25(OH)D level >50 nmol/L] but the majority of those aged above 65 years were deficient. A major role for exposure to solar ultraviolet radiation (UVR) in determining 25(OH)D levels was apparent, with the dietary contribution being minor. Limited data exist regarding the impact of recent changes in lifestyles on vitamin D status, such as urbanisation. With regard to disease susceptibility, 11 of 22 relevant publications indicated association between low 25(OH)D levels and disease, with deficiency most notably found in individuals with tuberculosis and HIV-1. Information on the relationship between vitamin D receptor variants and ethnicity, disease or treatment response in the South African population groups demonstrated complex interactions between genetics, epigenetics and the environment. Whether vitamin D plays an important role in protection against the range of diseases that currently constitute a large burden on the health services in South Africa requires further investigation. Only then can accurate advice be given about personal sun exposure or dietary vitamin D supplementation.

Genetic associations with viral respiratory illnesses and asthma control in children

BACKGROUND

Viral respiratory infections can cause acute wheezing illnesses in children and exacerbations of asthma.

OBJECTIVE

We sought to identify variation in genes with known antiviral and pro-inflammatory functions to identify specific associations with more severe viral respiratory illnesses and the risk of virus-induced exacerbations during the peak fall season.

METHODS

The associations between genetic variation at 326 SNPs in 63 candidate genes and 10 phenotypes related to viral respiratory infection and asthma control were examined in 226 children enrolled in the RhinoGen study. Replication of asthma control phenotypes was performed in 2128 children in the Copenhagen Prospective Study on Asthma in Childhood (COPSAC). Significant associations in RhinoGen were further validated using virus-induced wheezing illness and asthma phenotypes in an independent sample of 122 children enrolled in the Childhood Origins of Asthma (COAST) birth cohort study.

RESULTS

A significant excess of P values smaller than 0.05 was observed in the analysis of the 10 RhinoGen phenotypes. Polymorphisms in 12 genes were significantly associated with variation in the four phenotypes showing a significant enrichment of small P values. Six of those genes (STAT4, JAK2, MX1, VDR, DDX58, and EIF2AK2) also showed significant associations with asthma exacerbations in the COPSAC study or with asthma or virus-induced wheezing phenotypes in the COAST study.

CONCLUSIONS

We identified genetic factors contributing to individual differences in childhood viral respiratory illnesses and virus-induced exacerbations of asthma. Defining mechanisms of these associations may provide insight into the pathogenesis of viral respiratory infections and virus-induced exacerbations of asthma.

Vitamin D deficiency and lower respiratory tract infections in children: a systematic review and meta-analysis of observational studies

Studies related to vitamin D deficiency and lower respiratory tract infections (LRTI) in children have inconsistent findings. The objective of this systematic review was to assess the prevalence of vitamin D deficiency in children with LRTI, and to evaluate the correlation between vitamin D levels and the incidence and severity of LRTI. A total of 12 studies enrolling 2279 participants were included in our analysis. Children with LRTI were found to have significantly lower mean vitamin D levels as compared to controls There was likewise a correlation between vitamin D levels and incidence and severity of LRTI. Large randomised controlled trials are needed to evaluate effect of vitamin D supplementation for LRTI.

Genetic association of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C-159T polymorphisms with the risk of severe RSV infection: a meta-analysis

Respiratory syncytial virus (RSV) is the most frequent cause of hospitalization in infants worldwide. It is recognized by Toll‐like receptor 4 (TLR 4) and cluster of differentiation 14 (CD14) in the innate immune response. Previous case–control studies reported the influence of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms on the risk of severe RSV infection. However, a decisive conclusion has not been achieved. Therefore, we performed this meta‐analysis to examine the association between these three polymorphisms and the development of RSV bronchiolitis. A systematic literature search was performed using the PubMed, EMbase, Google Scholar Search, China National Knowledge Infrastructure, China Biological Medicine, and Wanfang Databases. The data were extracted and pooled odds ratios with 95% confidence intervals were calculated under six genetic models. A total of six studies with 1009 cases and 1348 controls, three studies with 473 cases and 481 controls, or four studies with 325 cases and 650 controls relating to each of the three polymorphisms were included in this meta‐analysis. The analyzed data indicated that all of these polymorphisms were not associated with the risk of severe RSV infection. This is the first meta‐analysis to investigate the relationship of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms with the risk of severe RSV infection. Although the results of this retrospective analysis indicated a lack of the association, more extensive multicentric studies with large sample sizes are necessary to provide a more reliable estimation of the association between these three polymorphisms and RSV bronchiolitis susceptibility.

Association of Vitamin D Receptor Polymorphism with Susceptibility to Symptomatic Pertussis

Pertussis, caused by infection with the gram negative B. pertussis bacterium, is a serious respiratory illness that can last for months. While B. pertussis infection rates are estimated between 1-10% in the general population, notifications of symptomatic pertussis only comprise 0.01-0.1% indicating that most individuals clear B. pertussis infections without developing (severe) clinical symptoms. In this study we investigated whether genetic risk factors are involved in the development of symptomatic pertussis upon B. pertussis infection. Single-nucleotide polymorphisms (SNPs) in candidate genes, MBL2, IL17A, TNFα, VDR, and IL10 were genotyped in a unique Dutch cohort of symptomatic clinically confirmed (ex-)pertussis patients and in a Dutch population cohort. Of the seven investigated SNPs in five genes, a polymorphism in the Vitamin D receptor (VDR) gene (rs10735810) was associated with pertussis. The VDR major allele and its homozygous genotype were more present in the symptomatic pertussis patient cohort compared to the control population cohort. Interestingly, the VDR major allele correlated also with the duration of reported pertussis symptoms. Vitamin D3 (VD3) and VDR are important regulators of immune activation. Altogether, these findings suggest that polymorphisms in the VDR gene may affect immune activation and the clinical outcome of B. pertussis infection.

Risk of respiratory syncytial virus infection in preterm infants: reviewing the need for prevention

Premature infants are at substantial risk for a spectrum of morbidities that are gestational age dependent. Respiratory syncytial virus (RSV) infection is most common in the first two years of life with the highest burden in children aged <6 months. Preterm infants ≤35 weeks' gestation are handicapped by incomplete immunological and pulmonary maturation and immature premorbid lung function with the added risk of bronchopulmonary dysplasia. Superimposed RSV infection incites marked neutrophilic airway inflammation and innate immunological responses that further compromise normal airway modeling. This review addresses the epidemiology and burden of RSV disease, focusing on the preterm population. Risk factors that determine RSV-disease severity and hospitalization and the impact on healthcare resource utilization and potential long-term respiratory sequelae are discussed. The importance of disease prevention and the evidence-based rationale for prophylaxis with palivizumab is explored, while awaiting the development of a universal vaccine.

Genes associated with RSV lower respiratory tract infection and asthma: the application of genetic epidemiological methods to understand causality

Infants with respiratory syncytial virus (RSV) lower respiratory tract infections (LRIs) are at increased risk for childhood asthma. The objectives of this article are to review the genes associated with both RSV LRI and asthma, review analytic approaches to assessing shared genetic risk and propose a future perspective on how these approaches can help us to understand the role of infant RSV infection as both an important risk factor for asthma and marker of shared genetic etiology between the two conditions. The review of shared genes and thus pathways associated with severity of response to RSV infection and asthma risk can help us to understand mechanisms of disease and ultimately propose new and novel targets for primary prevention of both diseases.

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.

Challenges and opportunities in developing respiratory syncytial virus therapeutics

Two meetings, one sponsored by the Wellcome Trust in 2012 and the other by the Global Virology Foundation in 2013, assembled academic, public health and pharmaceutical industry experts to assess the challenges and opportunities for developing antivirals for the treatment of respiratory syncytial virus (RSV) infections. The practicalities of clinical trials and establishing reliable outcome measures in different target groups were discussed in the context of the regulatory pathways that could accelerate the translation of promising compounds into licensed agents. RSV drug development is hampered by the perceptions of a relatively small and fragmented market that may discourage major pharmaceutical company investment. Conversely, the public health need is far too large for RSV to be designated an orphan or neglected disease. Recent advances in understanding RSV epidemiology, improved point-of-care diagnostics, and identification of candidate antiviral drugs argue that the major obstacles to drug development can and will be overcome. Further progress will depend on studies of disease pathogenesis and knowledge provided from controlled clinical trials of these new therapeutic agents. The use of combinations of inhibitors that have different mechanisms of action may be necessary to increase antiviral potency and reduce the risk of resistance emergence.

Vitamin D as an adjunctive therapy in asthma. Part 1: A review of potential mechanisms

Vitamin D deficiency (VDD) is highly prevalent worldwide. The classical role for vitamin D is to regulate calcium absorption form the gastrointestinal tract and influence bone health. Recently vitamin D receptors and vitamin D metabolic enzymes have been discovered in numerous sites systemically supporting diverse extra-skeletal roles of vitamin D, for example in asthmatic disease. Further, VDD and asthma share several common risk factors including high latitude, winter season, industrialization, poor diet, obesity, and dark skin pigmentation. Vitamin D has been demonstrated to possess potent immunomodulatory effects, including effects on T cells and B cells as well as increasing production of antimicrobial peptides (e.g. cathelicidin). This immunomodulation may lead to asthma specific clinical benefits in terms of decreased bacterial/viral infections, altered airway smooth muscle-remodeling and -function as well as modulation of response to standard anti-asthma therapy (e.g. glucocorticoids and immunotherapy). Thus, vitamin D and its deficiency have a number of biological effects that are potentially important in altering the course of disease pathogenesis and severity in asthma. The purpose of this first of a two-part review is to review potential mechanisms whereby altering vitamin D status may influence asthmatic disease.

TLR4 genotype and environmental LPS mediate RSV bronchiolitis through Th2 polarization

While 30%-70% of RSV-infected infants develop bronchiolitis, 2% require hospitalization. It is not clear why disease severity differs among healthy, full-term infants; however, virus titers, inflammation, and Th2 bias are proposed explanations. While TLR4 is associated with these disease phenotypes, the role of this receptor in respiratory syncytial virus (RSV) pathogenesis is controversial. Here, we evaluated the interaction between TLR4 and environmental factors in RSV disease and defined the immune mediators associated with severe illness. Two independent populations of infants with RSV bronchiolitis revealed that the severity of RSV infection is determined by the TLR4 genotype of the individual and by environmental exposure to LPS. RSV-infected infants with severe disease exhibited a high GATA3/T-bet ratio, which manifested as a high IL-4/IFN-γ ratio in respiratory secretions. The IL-4/IFN-γ ratio present in infants with severe RSV is indicative of Th2 polarization. Murine models of RSV infection confirmed that LPS exposure, Tlr4 genotype, and Th2 polarization influence disease phenotypes. Together, the results of this study identify environmental and genetic factors that influence RSV pathogenesis and reveal that a high IL-4/IFN-γ ratio is associated with severe disease. Moreover, these molecules should be explored as potential targets for therapeutic intervention.

Host-Viral Interactions: Role of Pattern Recognition Receptors (PRRs) in Human Pneumovirus Infections

Acute respiratory tract infection (RTI) is a leading cause of morbidity and mortality worldwide and the majority of RTIs are caused by viruses, among which respiratory syncytial virus (RSV) and the closely related human metapneumovirus (hMPV) figure prominently. Host innate immune response has been implicated in recognition, protection and immune pathological mechanisms. Host-viral interactions are generally initiated via host recognition of pathogen-associated molecular patterns (PAMPs) of the virus. This recognition occurs through host pattern recognition receptors (PRRs) which are expressed on innate immune cells such as epithelial cells, dendritic cells, macrophages and neutrophils. Multiple PRR families, including Toll-like receptors (TLRs), RIG-I-like receptors (RLRs) and NOD-like receptors (NLRs), contribute significantly to viral detection, leading to induction of cytokines, chemokines and type I interferons (IFNs), which subsequently facilitate the eradication of the virus. This review focuses on the current literature on RSV and hMPV infection and the role of PRRs in establishing/mediating the infection in both in vitro and in vivo models. A better understanding of the complex interplay between these two viruses and host PRRs might lead to efficient prophylactic and therapeutic treatments, as well as the development of adequate vaccines.

Vitamin D-binding protein haplotype is associated with hospitalization for RSV bronchiolitis

BACKGROUND

Between 75 000 and 125 000 U.S. infants are hospitalized for respiratory syncytial virus (RSV) bronchiolitis every year. Up to half will be diagnosed with asthma in later childhood. Vitamin D deficiency has been associated with susceptibility to asthma and respiratory infections. Measured vitamin D is largely bound to vitamin D-binding protein (VDBP); VDBP levels are influenced by its gene (GC) haplotype.

OBJECTIVE

We assessed the relationship between polymorphisms rs7041 and rs4588, which define haplotypes GC1s, GC1f, and GC2, and RSV bronchiolitis susceptibility and subsequent asthma.

METHODS

We retrospectively recruited 198 otherwise healthy children (93% White) hospitalized for severe RSV bronchiolitis in Boston and 333 parents into a follow-up study to assess asthma diagnosis. Data were analysed using family-based genetic association tests. We independently validated our results in 465 White children hospitalized with RSV bronchiolitis and 930 White population controls from the Netherlands.

RESULTS

The rs7041_C allele (denoting haplotype GC1s) was overtransmitted (P = 0.02, additive model) in the entire Boston cohort, in Whites (P = 0.03), and especially in children subsequently diagnosed with asthma (P = 0.006). The GC1f haplotype was undertransmitted in the asthma subgroups (all races and White, both P < 0.05). The rs7041_C allele was also more frequent in the RSV bronchiolitis group compared with controls (OR 1.12, 95% CI 1.02, 1.4, P = 0.03) in the Netherlands, especially in mechanically ventilated patients (P = 0.009).

CONCLUSION AND CLINICAL RELEVANCE

GC1s haplotype carriage may increase the risk of RSV bronchiolitis in infancy and subsequent asthma development. The GC1s haplotype is associated with higher VDBP levels, resulting in less freely available vitamin D.

KEY MESSAGES

Vitamin D-binding protein (VDBP) haplotypes influence free vitamin D levels. We report an association between a VDBP haplotype and hospitalization for RSV bronchiolitis in infancy in two independent cohorts.

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.

Association of vitamin D receptor gene polymorphisms and bronchopulmonary dysplasia

BACKGROUND

Vitamin D and its receptor (VDR) have important roles in perinatal lung development. The aim of this study was to investigate the relationship between VDR gene polymorphism and bronchopulmonary dysplasia (BPD) in preterm infants.

METHODS

VDR Fok I, Bsm I, Apa I, and Taq I polymorphisms were genotyped using restriction fragment length polymorphism in 109 preterm infants (47 with BPD, 62 without BPD).

RESULTS

In univariate analysis, Ff (odds ratio (OR) = 3.937, P = 0.022, 95% confidence interval (CI) = 1.22-12.69) and ff (OR = 5.23, P = 0.004, 95% CI = 1.69-16.23) genotypes of Fok I were associated with the increased risk of BPD; whereas tt genotype of Taq 1 was associated with a protective effect against BPD (OR = 0.30, P = 0.04, 95% CI = 0.09-0.94). In multivariate logistic regression analysis, variant Fok 1 genotype increased risk of BPD (OR = 4.11, 95% CI = 1.08-15.68, P = 0.038) independent of patent ductus arteriosus, sepsis, mechanical ventilation, and surfactant treatment. Taq 1, Bsm 1, and Apa 1 polymorphisms did not have any effect.

CONCLUSION

After adjusting for multiple confounders, VDR Fok 1 polymorphism was associated with the increased frequency of BPD. Further studies are needed to assess the contribution of VDR signaling to the pathogenesis of BPD and to determine if VDR polymorphisms may be suitable for identifying infants at high risk for BPD.

A systematic review of predictive modeling for bronchiolitis

PURPOSE

Bronchiolitis is the most common cause of illness leading to hospitalization in young children. At present, many bronchiolitis management decisions are made subjectively, leading to significant practice variation among hospitals and physicians caring for children with bronchiolitis. To standardize care for bronchiolitis, researchers have proposed various models to predict the disease course to help determine a proper management plan. This paper reviews the existing state of the art of predictive modeling for bronchiolitis. Predictive modeling for respiratory syncytial virus (RSV) infection is covered whenever appropriate, as RSV accounts for about 70% of bronchiolitis cases.

METHODS

A systematic review was conducted through a PubMed search up to April 25, 2014. The literature on predictive modeling for bronchiolitis was retrieved using a comprehensive search query, which was developed through an iterative process. Search results were limited to human subjects, the English language, and children (birth to 18 years).

RESULTS

The literature search returned 2312 references in total. After manual review, 168 of these references were determined to be relevant and are discussed in this paper. We identify several limitations and open problems in predictive modeling for bronchiolitis, and provide some preliminary thoughts on how to address them, with the hope to stimulate future research in this domain.

CONCLUSIONS

Many problems remain open in predictive modeling for bronchiolitis. Future studies will need to address them to achieve optimal predictive models.

Genetic predisposition of RSV infection-related respiratory morbidity in preterm infants

The aim of this study was to assess whether prematurely born infants have a genetic predisposition to respiratory syncytial virus (RSV) infection-related respiratory morbidity. One hundred and forty-six infants born at less than 36 weeks of gestation were prospectively followed. Nasopharygeal aspirates were obtained on every occasion the infants had a lower respiratory tract infection (LRTI) regardless of need for admission. DNA was tested for 11 single-nucleotide polymorphisms (SNPs). Chronic respiratory morbidity was assessed using respiratory health-related questionnaires, parent-completed diary cards at a corrected age of 1 year and review of hospital notes. Lung function was measured at a post menstrual age (PMA) of 36 weeks and corrected age of 1 year. A SNP in ADAM33 was associated with an increased risk of developing RSV LRTIs, but not with significant differences in 36-week PMA lung function results. SNPs in several genes were associated with increased chronic respiratory morbidity (interleukin 10 (IL10), nitric oxide synthase 2A (NOS2A), surfactant protein C (SFTPC), matrix metalloproteinase 16 (MMP16) and vitamin D receptor (VDR)) and reduced lung function at 1 year (MMP16, NOS2A, SFTPC and VDR) in infants who had had RSV LRTIs.

CONCLUSIONS

Our results suggest that prematurely born infants may have a genetic predisposition to RSV LRTIs and subsequent respiratory morbidity which is independent of premorbid lung function.