Interleukin 13 exposure enhances vitamin D-mediated expression of the human cathelicidin antimicrobial peptide 18/LL-37 in bronchial epithelial cells

Allergic fungal rhinosinusitis linked to other hyper-IgE syndromes through defective TH17 responses

BACKGROUND

In a gene expression analysis comparing sinus mucosa samples from allergic fungal rhinosinusitis (AFRS) patients with samples from non-AFRS chronic rhinosinusitis with nasal polyp (CRSwNP) patients, the antimicrobial peptide (AMP) histatin 1 (HTN1) was found to be the most differentially downregulated gene in AFRS.

OBJECTIVE

We sought to identify the molecular etiology of the downregulated expression of HTN1.

METHODS

We used RT-PCR to compare the expression of AMPs and a fungistasis assay to evaluate the antifungal activity of sinus secretions. Using flow cytometry, we characterized the presence of TH17/TH22 cells and signal transducer and activator of transcription (STAT) signaling from AFRS patients, non-AFRS CRSwNP patients, and healthy controls.

RESULTS

We confirmed decreased expression of AMPs in AFRS sinus mucosa with concordant decrease in antifungal activity in sinus secretions. IL-22 and IL-22-producing T cells were deficient within sinus mucosa of AFRS patients. In vitro studies demonstrated a defect in IL-6/STAT3 signaling critical for TH17/TH22 differentiation. Epithelial cells from AFRS patients could express AMPs when stimulated with exogenous IL-22/IL-17 and circulating TH17 cell abundance was normal.

CONCLUSIONS

Similar to other hyper-IgE syndromes, but distinct from CRSwNP, AFRS patients express a defect in STAT3 activation limited to IL-6-dependent STAT3 phosphorylation that is critical for TH17/TH22 differentiation. This defect leads to a local deficiency of IL-17/IL-22 cytokines and deficient AMP expression within diseased sinus mucosa of AFRS patients. Our findings support evaluation of therapeutic approaches that enhance airway AMP production in AFRS.

A Review of Genes Involved in Wound Healing

Background

Gene therapy holds immense potential in the field of wound healing. However, we still do not recognize this procedure well enough to give oversight effectively to improve healing processes. A wide range of information has been achieved from the database for gene expression profiling by clinical trials, So we performed this study to gain a better understanding of the mechanisms behind wound healing and how it could be utilized to develop new therapies and treatments.

Methods

In this study, we have been focusing on wound-healing genes, conducting a thorough review to explore the various genes and pathways involved in this process. For this purpose, a total of 320 articles were collected. All experimental studies, systematic or narrative reviews, studies and clinical trials included in this paper were searched on PubMed, Medline, Embase, Science Direct, and Scopus databases in English using the following terms: Wound Healing, wound regeneration, Gene Transfer, and Gene Therapy were used to search the mentioned databases. Unfortunately, we didn't find a large sample cohort study on this topic. A total amount of 330 articles were collected based on the guidelines of the PRISMA method. Both inclusion and exclusion criteria were settled.

Results

During the last decade, different models of gene delivery have been introduced, which include viral transfection and Non-viral techniques. In this regard, TIMP-2 protein and VEGF mutants such as VEGF165, CARP, and HIF-1 are the genes that accelerate the rate of tissue repair.

Conclusion

The process of wound healing is mainly related to the change of expression of genes that have a role in the parts of inflammation and repair. In our study, some of the most suitable genes involved in the wound-healing process are mentioned.

Role of antimicrobial peptide cathelicidin in thrombosis and thromboinflammation

Thrombosis is a frequent cause of cardiovascular mortality and hospitalization. Current antithrombotic strategies, however, target both thrombosis and physiological hemostasis and thereby increase bleeding risk. In recent years the pathophysiological understanding of thrombus formation has significantly advanced and inflammation has become a crucial element. Neutrophils as most frequent immune cells in the blood and their released mediators play a key role herein. Neutrophil-derived cathelicidin next to its strong antimicrobial properties has also shown to modulates thrombosis and thus presents a potential therapeutic target. In this article we review direct and indirect (immune- and endothelial cell-mediated) effects of cathelicidin on platelets and the coagulation system. Further we discuss its implications for large vessel thrombosis and consecutive thromboinflammation as well as immunothrombosis in sepsis and COVID-19 and give an outlook for potential therapeutic prospects.

Induction of Endogenous Antimicrobial Peptides to Prevent or Treat Oral Infection and Inflammation

Antibiotics are often used to treat oral infections. Unfortunately, excessive antibiotic use can adversely alter oral microbiomes and promote the development of antibiotic-resistant microorganisms, which can be difficult to treat. An alternate approach could be to induce the local transcription and expression of endogenous oral antimicrobial peptides (AMPs). To assess the feasibility and benefits of this approach, we conducted literature searches to identify (i) the AMPs expressed in the oral cavity; (ii) the methods used to induce endogenous AMP expression; and (iii) the roles that expressed AMPs may have in regulating oral inflammation, immunity, healing, and pain. Search results identified human neutrophil peptides (HNP), human beta defensins (HBD), and cathelicidin AMP (CAMP) gene product LL-37 as prominent AMPs expressed by oral cells and tissues. HNP, HBD, and LL-37 expression can be induced by micronutrients (trace elements, elements, and vitamins), nutrients, macronutrients (mono-, di-, and polysaccharides, amino acids, pyropeptides, proteins, and fatty acids), proinflammatory agonists, thyroid hormones, and exposure to ultraviolet (UV) irradiation, red light, or near infrared radiation (NIR). Localized AMP expression can help reduce infection, inflammation, and pain and help oral tissues heal. The use of a specific inducer depends upon the overall objective. Inducing the expression of AMPs through beneficial foods would be suitable for long-term health protection. Additionally, the specialized metabolites or concentrated extracts that are utilized as dosage forms would maintain the oral and intestinal microbiome composition and control oral and intestinal infections. Inducing AMP expression using irradiation methodologies would be applicable to a specific oral treatment area in addition to controlling local infections while regulating inflammatory and healing processes.

Deciphering the Function of New Therapeutic Targets and Prospective Biomarkers in the Management of Psoriasis

Psoriasis is an immune-mediated skin condition affecting people worldwide, presenting at any age, and leading to a substantial burden physically and mentally. The innate and adaptive immune systems interact intricately with the pathomechanisms that underlie disease. T cells can interact with keratinocytes, macrophages, and dendritic cells through the cytokines they secrete. According to recent research, psoriasis flare-ups can cause systemic inflammation and various other co-morbidities, including depression, psoriatic arthritis, and cardio-metabolic syndrome. Additionally, several auto-inflammatory and auto-immune illnesses may be linked to psoriasis. Although psoriasis has no proven treatment, care must strive by treating patients as soon as the disease surfaces, finding and preventing concurrent multimorbidity, recognising and reducing bodily and psychological distress, requiring behavioural modifications, and treating each patient individually. Biomarkers are traits that are assessed at any time along the clinical continuum, from the early stages of a disease through the beginning of treatment (the foundation of precision medicine) to the late stages of treatment (outcomes and endpoints). Systemic therapies that are frequently used to treat psoriasis provide a variety of outcomes. Targeted therapy selection, better patient outcomes, and more cost-effective healthcare would be made possible by biomarkers that reliably predict effectiveness and safety. This review is an attempt to understand the role of Antimicrobial peptides (AMP), Interleukin-38 (IL-38), autophagy 5 (ATG5) protein and squamous cell carcinoma antigen (SCCA) as biomarkers of psoriasis.

A Scoping Analysis of Cathelicidin in Response to Organic Dust Exposure and Related Chronic Lung Illnesses

Over two billion people worldwide are exposed to organic dust, which can cause respiratory disorders. The discovery of the cathelicidin peptide provides novel insights into the lung's response to organic dust; however, its role in the lung's response to organic dust exposure and chronic lung diseases remains limited. We conducted a scoping review to map the current evidence on the role of cathelicidin LL-37/CRAMP in response to organic dust exposure and related chronic lung diseases: hypersensitivity pneumonitis (HP), chronic obstructive pulmonary disease (COPD) and asthma. We included a total of n = 53 peer-reviewed articles in this review, following the process of (i) a preliminary screening; (ii) a systematic MEDLINE/PubMed database search; (iii) title, abstract and full-text screening; (iv) data extraction and charting. Cathelicidin levels were shown to be altered in all clinical settings investigated; its pleiotropic function was confirmed. It was found that cathelicidin contributes to maintaining homeostasis and participates in lung injury response and repair, in addition to exerting a positive effect against microbial load and infections. In addition, LL-37 was found to sustain continuous inflammation, increase mucus formation and inhibit microorganisms and corticosteroids. In addition, studies investigated cathelicidin as a treatment modality, such as cathelicidin inhalation in experimental HP, which had positive effects. However, the primary focus of the included articles was on LL-37's antibacterial effect, leading to the conclusion that the beneficial LL-37 activity has not been adequately examined and that further research is required.

Local nebulization of 1α,25(OH)2D3 attenuates LPS-induced acute lung inflammation

Background

Evidence supports a critical role of vitamin D status on exacerbation in chronic obstructive pulmonary disease, indicating the need to avoid vitamin D deficiency in these patients. However, oral vitamin D supplementation is limited by the potential risk for hypercalcemia. In this study, we investigated if local delivery of vitamin D to the lungs improves vitamin D-mediated anti-inflammatory action in response to acute inflammation without inducing hypercalcemia.

Methods

We studied vitamin D sufficient (VDS) or deficient (VDD) mice in whom 1α,25(OH)₂D₃ (0.2 μg/kg) or a vehicle followed by lipopolysaccharide (LPS 25 µg) were delivered to the lung as a micro-spray.

Results

Local 1α,25(OH)₂D₃ reduced LPS-induced inflammatory cells in bronchoalveolar lavage (BAL) in VDS (absolute number of cells: − 57% and neutrophils − 51% p < 0.01) and tended to diminish LPS-increased CXCL5 BAL levels in VDS (− 40%, p = 0.05) while it had no effect on CXCL1 and CXCL2 in BAL and mRNA in lung of VDS and VDD. It also significantly attenuated the increased IL-13 in BAL and lung, especially in VDD mice (− 41 and − 75%, respectively). mRNA expression of Claudin-18 in lung was significantly lower in VDS mice with local 1α,25(OH)₂D₃ while Claudin-3, -5 and -8 mRNA levels remained unchanged. Finally, in VDD mice only, LPS reduced lung mRNA expression of adhesion junction Zona-occludens-1, in addition to increasing uric acid and total protein in BAL, which both were prevented by local 1α,25(OH)₂D₃.

Conclusion

Under normal levels of vitamin D, local 1α,25(OH)₂D₃ nebulization into the lung efficiently reduced LPS induction of inflammatory cells in BAL and slightly attenuated LPS-increase in CXCL5. In case of severe vitamin D deficiency, although local 1α,25(OH)₂D₃ nebulization failed to significantly minimize cellular inflammation in BAL at this dose, it prevented epithelial barrier leakage and damage in lung. Additional research is needed to determine the potential long-term beneficial effects of local 1α,25(OH)2D3 nebulization on lung inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01997-9.

Vitamin D Status and Health Outcomes in School Children in Northern Ireland: Year One Results from the D-VinCHI Study

(1) Background: Vitamin D status has never been investigated in children in Northern Ireland (UK). (2) Methods: Children (4-11 years) (n = 47) were recruited from November 2019 to March 2020 onto the cross-sectional study. Anthropometry was assessed. Plasma 25-hydroxyvitamin D (25(OH)D) was analysed. Vitamin D intake, parental knowledge and perceptions, participant habits, physical activity and sedentary behaviour were established via questionnaire. Muscle strength was assessed via isometric grip strength dynamometry and balance via dominant single-leg and tandem stance. Parathyroid hormone, bone turnover markers (OC, CTX and P1NP), glycated haemoglobin and inflammatory markers (CRP, IFN-γ, IL-10, IL-12p70, IL-13, IL-1β, IL-2, IL-4, IL-6, IL-8 and TNF-α) were analysed. (3) Results: Mean (SD) 25(OH)D was 49.17 (17.04) nmol/L (n = 47); 44.7% of the children were vitamin D sufficient (25(OH)D >50 nmol/L), 48.9% were insufficient (25-50 nmol/L) and 6.4% were deficient (<25 nmol/L). 25(OH)D was positively correlated with vitamin D intake (µg/day) (p = 0.012, r = 0.374), spring/summer outdoor hours (p = 0.006, r = 0.402) and dominant grip strength (kg) (p = 0.044, r = 0.317). Vitamin D sufficient participants had higher dietary vitamin D intake (µg/day) (p = 0.021), supplement intake (µg/day) (p = 0.028) and spring/summer outdoor hours (p = 0.015). (4) Conclusion: Over half of the children were vitamin D deficient or insufficient. Wintertime supplementation, the consumption of vitamin D rich foods and spring/summer outdoor activities should be encouraged to minimise the risk of vitamin D inadequacy.

Vitamin D Actions: The Lung Is a Major Target for Vitamin D, FGF23, and Klotho

Vitamin D is well known for its role as a calcium regulator and in maintenance of phosphate homeostasis in musculoskeletal health, and fibroblast growth factor 23 (FGF23) and its coreceptor α-klotho are known for their roles as regulators of serum phosphate levels. However, apart from these classical actions, recent data point out a relevant role of vitamin D and FGF23/klotho in lung health. The expression of the vitamin D receptor by different cell types in the lung and the fact that those cells respond to vitamin D or can locally produce vitamin D indicate that the lung represents a target for vitamin D actions. Similarly, the presence of the four FGF receptor isoforms in the lung and the ability of FGF23 to stimulate pulmonary cells support the concept that the lung is a target for FGF23 actions, whereas the contribution of klotho is still undetermined. This review will give an overview on how vitamin D or FGF23/klotho may act on the lung and interfere positively or negatively with lung health. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Potential immunomodulatory effects of vitamin D in the prevention of severe coronavirus disease 2019: An ally for Latin America (Review)

Currently, the world is under a pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for coronavirus disease 2019 (COVID-19). This disease is characterized by a respiratory syndrome that can progress to an acute respiratory distress syndrome. To date, limited effective therapies are available for the prevention or treatment of COVID-19; therefore, it is necessary to propose novel treatment options with immunomodulatory effects. Vitamin D serves functions in bone health and has been recently reported to exert protective effects against respiratory infections. Observational studies have demonstrated an association between vitamin D deficiency and a poor prognosis of COVID-19; this is alarming as vitamin D deficiency is a global health problem. In Latin America, the prevalence of vitamin D deficiency is unknown, and currently, this region is in the top 10 according to the number of confirmed COVID-19 cases. Supplementation with vitamin D may be a useful adjunctive treatment for the prevention of COVID-19 complications. The present review provides an overview of the current knowledge of the potential immunomodulatory effects of vitamin D in the prevention of COVID-19 and sets out vitamin D recommendations for the Latin American population.

MECHANISMS IN ENDOCRINOLOGY: Vitamin D and COVID-19

The SARS-CoV-2 virus responsible for the COVID-19 pandemic has generated an explosion of interest both in the mechanisms of infection leading to dissemination and expression of this disease, and in potential risk factors that may have a mechanistic basis for disease propagation or control. Vitamin D has emerged as a factor that may be involved in these two areas. The focus of this article is to apply our current understanding of vitamin D as a facilitator of immunocompetence both with regard to innate and adaptive immunity and to consider how this may relate to COVID-19 disease. There are also intriguing potential links to vitamin D as a factor in the cytokine storm that portends some of the most serious consequences of SARS-CoV-2 infection, such as the acute respiratory distress syndrome. Moreover, cardiac and coagulopathic features of COVID-19 disease deserve attention as they may also be related to vitamin D. Finally, we review the current clinical data associating vitamin D with SARS-CoV-2 infection, a putative clinical link that at this time must still be considered hypothetical.

Cathelicidin Host Defense Peptides and Inflammatory Signaling: Striking a Balance

Host-defense peptides (HDPs) are vital components of innate immunity in all vertebrates. While their antibacterial activity toward bacterial cells was the original focus for research, their ability to modulate immune and inflammatory processes has emerged as one of their major functions in the host and as a promising approach from which to develop novel therapeutics targeting inflammation and innate immunity. In this review, with particular emphasis on the cathelicidin family of peptides, the roles of natural HDPs are examined in managing immune activation, cellular recruitment, cytokine responses, and inflammation in response to infection, as well as their contribution(s) to various inflammatory disorders and autoimmune diseases. Furthermore, we discuss current efforts to develop synthetic HDPs as therapeutics aimed at restoring balance to immune responses that are dysregulated and contribute to disease pathologies.

Antimicrobial activity of mesenchymal stem cells against Staphylococcus aureus

Introduction

There have been limited advances in the treatment of bone and joint infections, which currently involves a combination of surgery and antibiotic administration. There is a timely need in orthopedics to develop more effective and less invasive forms of antimicrobial prophylaxis and treatment. The antibacterial effect of adult tissue-derived mesenchymal stem cells (MSCs) has recently been investigated against Escherichia coli and Staphylococcus aureus. The main mechanism of action is postulated to be via MSC production of the cationic antimicrobial peptide, LL-37.

Methods

This study examines the antimicrobial activity of adipose-derived human MSCs (ASCs) on S. aureus, specifically examining the role of LL-37 and regulation of its expression. Bacteria colony-forming unit (CFU) assay was used to assess antimicrobial activity.

Results

Our results showed that the ASC-conditioned medium significantly inhibited the growth of S. aureus under standard culture conditions with or without the continued presence of ASCs. Also, the treatment of ASCs with 1,25-dihydroxy vitamin D₃ elevated LL-37 expression and enhanced their antimicrobial activity. In support, treatment with the vitamin D receptor inhibitor, GW0742, blocked the antimicrobial activity of ASCs.

Conclusion

Our findings clearly demonstrate the antimicrobial activity of adult ASCs against S. aureus and implicate a key regulatory role for vitamin D. Further testing in in vivo models is being pursued to assess the potential application of ASCs as a biocompatible, adjunct treatment for musculoskeletal infections.

Impact of the Local Inflammatory Environment on Mucosal Vitamin D Metabolism and Signaling in Chronic Inflammatory Lung Diseases

Vitamin D plays an active role in the modulation of innate and adaptive immune responses as well as in the protection against respiratory pathogens. Evidence for this immunomodulatory and protective role is derived from observational studies showing an association between vitamin D deficiency, chronic airway diseases and respiratory infections, and is supported by a range of experimental studies using cell culture and animal models. Furthermore, recent intervention studies have now shown that vitamin D supplementation reduces exacerbation rates in vitamin D-deficient patients with chronic obstructive pulmonary disease (COPD) or asthma and decreases the incidence of acute respiratory tract infections. The active vitamin D metabolite, 1,25-dihydroxy-vitamin D (1,25(OH)₂D), is known to contribute to the integrity of the mucosal barrier, promote killing of pathogens (via the induction of antimicrobial peptides), and to modulate inflammation and immune responses. These mechanisms may partly explain its protective role against infections and exacerbations in COPD and asthma patients. The respiratory mucosa is an important site of local 1,25(OH)₂D synthesis, degradation and signaling, a process that can be affected by exposure to inflammatory mediators. As a consequence, mucosal inflammation and other disease-associated factors, as observed in e.g., COPD and asthma, may modulate the protective actions of 1,25(OH)₂D. Here, we discuss the potential consequences of various disease-associated processes such as inflammation and exposure to pathogens and inhaled toxicants on vitamin D metabolism and local responses to 1,25(OH)₂D in both immune- and epithelial cells. We furthermore discuss potential consequences of disturbed local levels of 25(OH)D and 1,25(OH)₂D for chronic lung diseases. Additional insight into the relationship between disease-associated mechanisms and local effects of 1,25(OH)₂D is expected to contribute to the design of future strategies aimed at improving local levels of 1,25(OH)₂D and signaling in chronic inflammatory lung diseases.

Vitamin D-Cathelicidin Axis: at the Crossroads between Protective Immunity and Pathological Inflammation during Infection

Vitamin D signaling plays an essential role in innate defense against intracellular microorganisms via the generation of the antimicrobial protein cathelicidin. In addition to directly binding to and killing a range of pathogens, cathelicidin acts as a secondary messenger driving vitamin D-mediated inflammation during infection. Recent studies have elucidated the biological and clinical functions of cathelicidin in the context of vitamin D signaling. The vitamin D-cathelicidin axis is involved in the activation of autophagy, which enhances antimicrobial effects against diverse pathogens. Vitamin D studies have also revealed positive and negative regulatory effects of cathelicidin on inflammatory responses to pathogenic stimuli. Diverse innate and adaptive immune signals crosstalk with functional vitamin D receptor signals to enhance the role of cathelicidin action in cell-autonomous effector systems. In this review, we discuss recent findings that demonstrate how the vitamin D-cathelicidin pathway regulates autophagy machinery, protective immune defenses, and inflammation, and contributes to immune cooperation between innate and adaptive immunity. Understanding how the vitamin D-cathelicidin axis operates in the host response to infection will create opportunities for the development of new therapeutic approaches against a variety of infectious diseases.

Vitreous D-Lactate Levels as a Biomarker in the Diagnosis of Presumed Infectious Culture Negative Endophthalmitis

Purpose: Microbiological investigations of vitreous fluid have often failed to detect the causative agent in infectious endophthalmitis resulting in a clinical dilemma. D-Lactate is a byproduct of bacterial metabolism, and its accumulation in sterile body fluids indicates bacterial infection. The aim of the study was to evaluate the measurement of vitreous fluid D-lactate for the diagnosis of infectious endophthalmitis and to define an optimal D-lactate concentration for the differentiation from non-infectious samples.Methods: Vitreous samples of 41 patients clinically diagnosed as endophthalmitis and 20 patients with non-infectious disorders, as controls, between October 2018 and February 2019 were included in the study. D-lactate levels were determined by a D-lactate colorimetric assay kit (MAK058 Sigma-Aldrich) and the receiver operating characteristic curves (ROC) of D-lactate were calculated. The clinical finding of D-lactate production in bacterial endophthalmitis was also verified in a mouse model of bacterial endophthalmitis.Results: Of the 41 patients included in the infectious group, 25 had culture-positive infections of which 13/25 were gram-positive organisms and 12/25 grew gram-negative bacilli. Based on the ROC curve, the sensitivity of D-lactate was found to be 80% and specificity 100% and a cut-off value of above 47.06 ng/µl for D-lactate was defined as positive or true infectious in vitreous samples for diagnosis of endophthalmitis. In-vivo, a mouse model of bacterial endophthalmitis showed the significant production of D-lactate levels in retina and vitreous. Interestingly the levels were elevated in Gram-negative infections compared to Gram-positive bacterial endophthalmitis.Conclusion: Our clinical and in-vivo mouse model data showed that vitreous fluid D-lactate could be used as a bacterial-specific biomarker in the diagnosis of most infectious endophthalmitis and could be implemented for the evaluation of treatment success.

Immunological considerations in the development of Pseudomonas aeruginosa vaccines

Pseudomonas aeruginosa is an opportunistic human pathogen capable of causing a wide range of potentially life-threatening infections. With multidrug-resistant P. aeruginosa infections on the rise, the need for a rationally-designed vaccine against this pathogen is critical. A number of vaccine platforms have shown promising results in pre-clinical studies, but no vaccine has successfully advanced to licensure. Growing evidence suggests that an effective P. aeruginosa vaccine may require Th17-type CD4⁺ T cells to prevent infection. In this review, we summarize recent pre-clinical studies of P. aeruginosa vaccines, specifically focusing on those that induce Th17-type cellular immunity. We also highlight the importance of adjuvant selection and immunization route in vaccine design in order to target vaccine-induced immunity to infected tissues. Advances in cellular immunology and adjuvant biology may ultimately influence better P. aeruginosa vaccine platforms that can protect targeted human populations.

The delicate balance between Entamoeba histolytica, mucus and microbiota

Entamoeba histolytica (Eh) is a protozoan parasite of humans that colonizes the outer colonic mucus layer. Under conditions not fully understood, Eh breaches innate host defenses and invades the intestinal mucosa-causing amebic colitis and liver abscess. In asymptomatic infection, Eh interacts with and feeds on resident microbiota that forms biofilms on the outer colonic mucus layer. Despite the close association between Eh and commensal microbiota, we still lack basic knowledge on whether microbiota and/or their metabolites influence Eh virulence traits critical in disease pathogenesis. In the pathogenesis of intestinal amebiasis, Eh overcomes the protective mucus layer using a combination of mucinase/glycosidase and potent mucus secretagogue activity. In this addendum, we discuss the interconnected role of a healthy mucus barrier and the role commensal microbiota play in shaping innate host defense against Eh-induced pro-inflammatory and secretory responses critical in disease pathogenesis.

TGF-β1 Impairs Vitamin D-Induced and Constitutive Airway Epithelial Host Defense Mechanisms

Airway epithelium is an important site for local vitamin D (VD) metabolism; this can be negatively affected by inflammatory mediators. VD is an important regulator of respiratory host defense, for example, by increasing the expression of hCAP18/LL-37. TGF-β1 is increased in chronic obstructive pulmonary disease (COPD), and known to decrease the expression of constitutive host defense mediators such as secretory leukocyte protease inhibitor (SLPI) and polymeric immunoglobulin receptor (pIgR). VD has been shown to affect TGF-β1-signaling by inhibiting TGF-β1-induced epithelial-to-mesenchymal transition. However, interactions between VD and TGF-β1, relevant for the understanding host defense in COPD, are incompletely understood. Therefore, the aim of the present study was to investigate the combined effects of VD and TGF-β1 on airway epithelial cell host defense mechanisms. Exposure to TGF-β1 reduced both baseline and VD-induced expression of hCAP18/LL-37, partly by increasing the expression of the VD-degrading enzyme CYP24A1. TGF-β1 alone decreased the number of secretory club and goblet cells and reduced the expression of constitutive host defense mediators SLPI, s/lPLUNC and pIgR, effects that were not modulated by VD. These results suggest that TGF-β1 may decrease the respiratory host defense both directly by reducing the expression of host defense mediators, and indirectly by affecting VD-mediated effects such as expression of hCAP18/LL-37.

Negative correlation between testosterone and TNF-α in umbilical cord serum favors a weakened immune milieu in the human male fetoplacental unit

Clinical and epidemiological evidence supports that pregnancies carrying a male fetus are more vulnerable to infections and preterm birth, probably due to testosterone immunosuppressive properties. In human placentas, testosterone lowers the expression of CYP27B1, the vitamin D (VD)-activating enzyme, diminishing cathelicidin synthesis, a potent VD-dependent antimicrobial peptide (AMP). VD also stimulates other AMPs, including defensins. To get insights into the increased male vulnerability mechanisms, we investigated the relationship between fetal sex and the immunoendocrine milieu at the fetoplacental unit. For this, umbilical vein serum and placental samples were collected from healthy newborns. In males' serum, testosterone levels were significantly higher and negatively associated with TNF-α, a cytokine that strengthens the immune response. Males showed lower serum TNF-α and increased levels and gene expression of the immunosuppressive cytokine IL-10. Only in female samples there was a positive association (P < 0.05) between AMPs and both TNF-α and CYP27B1 and between 25-hydroxyvitamin D₃ and IL-1β serum levels. Accordingly, VD-metabolites (25-hydroxyvitamin D₃, calcitriol) significantly stimulated IL-1β gene expression in cultured trophoblasts. Interestingly, IL-1β mRNA correlated positively with defensins (P < 0.05) in males, but not with cathelicidin expression, which was significantly diminished in comparison to females. Our data suggest that high umbilical serum testosterone and IL-10 in males could explain reduced TNF-α levels and lack of association between VD-dependent innate immunity markers and proinflammatory cytokines expression in the fetoplacental unit. Altogether, our observations imply a restricted basal immune milieu in males compared to females, which may help understand the higher male susceptibility to adverse perinatal outcomes.

Upregulated expression of human cathelicidin LL-37 in hypercholesterolemia and its relationship with serum lipid levels

Dyslipidemia in patients with hypercholesterolemia has been recently linked to increased human cathelicidin LL-37 (LL-37) serum concentration. We tested a hypothesis that upregulated expression of LL-37 gene in peripheral blood leucocytes is involved in dyslipidemia in patients with hypercholesteremia. Patients with hypercholesterolemia were used in the study. Expression of LL-37 and human glyceraldehyde-3-phosphate dehydrogenase in peripheral blood leucocytes were quantified by real-time RT-PCR. Serum LL-37 concentration was estimated by enzyme-linked immunosorbent assay. Serum lipid levels were assessed by absorptiometry in all cases. Patients with hypercholesterolemia as compared to control ones were characterized by (a) an up-regulation of LL-37 gene expression in peripheral blood leucocytes with parallel increase of serum LL-37 concentration and (b) an increase of serum total and low-density lipoprotein cholesterol concentrations. Patients with hypercholesterolemia after a treatment with atorvastatin calcium 20 mg daily as compared to that patients before the treatment: an down-regulation of LL-37 gene expression in peripheral blood leucocytes with parallel decrease of serum LL-37 concentration. We also found significant correlation between serum LL-37 and high-density lipoprotein cholesterol levels (r = 0.7290, P < 0.0001). The results suggest that hypercholesterolemia is associated with an increased LL-37 gene expression in peripheral blood leucocytes. The correlation between serum LL-37 and high-density lipoprotein cholesterol levels suggests that LL-37 may play a key role in regulation of cholesterol levels in hypercholesterolemia.

Effects of human interleukins in the transgenic gene reporter cell lines IZ-VDRE and IZ-CYP24 designed to assess the transcriptional activity of vitamin D receptor

The role of vitamin D receptor (VDR) in immune responses has been broadly studied and it has been shown that activated VDR alters the levels of some interleukins (ILs). In this study, we studied the opposite, i.e. whether 13 selected pro-inflammatory and anti-inflammatory ILs influence the transcriptional activity of human VDR. The experimental models of choice were two human stably transfected gene reporter cell lines IZ-VDRE and IZ-CYP24, which were designed to evaluate the transcriptional activity of VDR. The gene reporter assays revealed inhibition of calcitriol-induced luciferase activity by IL-4 and IL-13, when 1 ng/mL of these two compounds decreased the effect of calcitriol down to 60% of the control value. Consistently, calcitriol-induced expression of CYP24A1 mRNA was also significantly decreased by IL-4 and IL-13. The expression of VDR and CYP27B1 mRNAs was not influenced by any of the 13 tested ILs. These data suggest possible cross-talk between the VDR signalling pathway and IL-4- and IL-13-mediated cell signalling.

Proinflammatory Cytokines Impair Vitamin D-Induced Host Defense in Cultured Airway Epithelial Cells

Vitamin D is a regulator of host defense against infections and induces expression of the antimicrobial peptide hCAP18/LL-37. Vitamin D deficiency is associated with chronic inflammatory lung diseases and respiratory infections. However, it is incompletely understood if and how (chronic) airway inflammation affects vitamin D metabolism and action. We hypothesized that long-term exposure of primary bronchial epithelial cells to proinflammatory cytokines alters their vitamin D metabolism, antibacterial activity, and expression of hCAP18/LL-37. To investigate this, primary bronchial epithelial cells were differentiated at the air-liquid interface for 14 days in the presence of the proinflammatory cytokines, TNF-α and IL-1β (TNF-α/IL-1β), and subsequently exposed to vitamin D (inactive 25(OH)D₃ and active 1,25(OH)₂D₃). Expression of hCAP18/LL-37, vitamin D receptor, and enzymes involved in vitamin D metabolism (CYP24A1 and CYP27B1) was determined using quantitative PCR, Western blot, and immunofluorescence staining. Furthermore, vitamin D-mediated antibacterial activity was assessed using nontypeable Haemophilus influenzae. We found that TNF-α/IL-1β treatment reduced vitamin D-induced expression of hCAP18/LL-37 and killing of nontypeable H. influenzae. In addition, CYP24A1 (a vitamin D-degrading enzyme) was increased by TNF-α/IL-1β, whereas CYP27B1 (that converts 25(OH)D₃ to its active form) and vitamin D receptor expression remained unaffected. Furthermore, we have demonstrated that the TNF-α/IL-1β-mediated induction of CYP24A1 was, at least in part, mediated by the transcription factor specific protein 1, and the epidermal growth factor receptor-mitogen-activated protein kinase pathway. These findings indicate that TNF-α/IL-1β decreases vitamin D-mediated antibacterial activity and hCAP18/LL-37 expression via induction of CYP24A1 and suggest that chronic inflammation impairs protective responses induced by vitamin D.

The licorice pentacyclic triterpenoid component 18β-glycyrrhetinic acid enhances the activity of antibiotics against strains of methicillin-resistant Staphylococcus aureus

This study aimed to identify compounds that enhance the activity of current antibiotics against multidrug-resistant bacteria. Screening of a 350+ compound proprietary small molecules library revealed that the Glycyrrhiza glabra (licorice)-derived triterpenoid 18β-glycyrrhetinic acid (18β-GA) potentiated the antibacterial activity of certain antibiotics against Staphylococcus aureus. Here, we evaluated the ability of pentacyclic triterpenoids to potentiate the activity of antibiotics against strains of methicillin-resistant S. aureus (MRSA). Checkerboard assays were used to assess the minimum inhibitory concentration (MIC) of tobramycin and ten pentacyclic triterpenoids against S. aureus. The effect of 18β-GA on the MIC of different antibiotics against MRSA was also determined in an in vitro airway MRSA infection model. 18β-GA enhanced the bactericidal activity of the aminoglycosides tobramycin, gentamicin and amikacin, and of polymyxin B against two MRSA strains, reducing the MIC of these antibiotics 32-64-fold [fractional inhibitory concentration index (FICI) of 0.12-0.13]. Other β-amyrin triterpenoids and α-amyrin triterpenoids did not exert such synergistic effects. 18β-GA did not enhance the activity of antibiotics from other structural classes against the MRSA strains. In an air-exposed airway epithelial cell culture, 18β-GA enhanced the bactericidal activity of tobramycin and polymyxin B against the MRSA strain. These data demonstrate the potential of 18β-GA to synergise with certain types of antibiotics to eliminate strains of MRSA.

Nasal Levels of Antimicrobial Peptides in Allergic Asthma Patients and Healthy Controls: Differences and Effect of a Short 1,25(OH)2 Vitamin D3 Treatment

Background

Allergy is often accompanied by infections and lower levels of antimicrobial peptides (AMPs). Vitamin D has been shown to increase expression of selected AMPs. In this study we investigated whether antimicrobial peptide levels in nasal secretions of allergic asthma patients are lower than in healthy controls, and whether administration of the active form of vitamin D (1,25(OH)₂D3) affects these antimicrobial peptide levels.

Methods

The levels of antimicrobial peptides in nasal secretions were compared between 19 allergic asthma patients and 23 healthy controls. The effect of seven days daily oral treatment with 2 μg 1,25(OH)₂D3 on antimicrobial peptides in nasal secretions was assessed in a placebo-controlled cross-over clinical study.

Results

Levels of neutrophil α-defensins (human neutrophil peptides 1–3; HNP1-3) and lipocalin 2 (LCN2; also known as NGAL) were significantly lower in asthmatics, but no differences in LL-37 and SLPI were detected. Treatment with a short-term 1,25(OH)₂D3 caused a small increase in HNP1-3, but not when the asthma and control groups were analyzed separately. LL-37, LCN2 and SLPI did not change after treatment with 1,25(OH)₂D3.

Conclusion

Levels of the antimicrobial peptides HNP1-3 and LCN2 are lower in nasal secretions in asthmatics and are not substantially affected by a short-term treatment with active vitamin D.

Association between vitamin D and respiratory outcomes in Canadian adolescents and adults

BACKGROUND

Asthma is one of the most prevalent chronic diseases worldwide, affecting more than 200 million people. Vitamin D deficiency has been reported among individuals with asthma and might play a role in asthma exacerbations. In this cross-sectional study, we investigated the association of serum 25-hydroxy vitamin D [25(OH)D] levels and current asthma, ever asthma, and lung function.

METHODS

Data from 3937 subjects aged 13-69 years who participated in the Canadian Health Measures Survey - Cycle 1 were considered in this study. Serum 25(OH)D levels were categorized into ≤49 nmol/L (low), 50-74 nmol/L (moderate) and ≥75 nmol/L (high).

RESULTS

The proportion of subjects with current and ever asthma was greater in the lower 25(OH)D category than in moderate and high categories. After adjusting for potential confounders, subjects in the low 25(OH)D levels were more likely to have current asthma than those in the moderate levels (OR: 1.54, 95% CI: 1.01-2.36). Low 25(OH)D levels were also associated with ever asthma (OR: 2.12, 95% CI: 1.40-3.21) among those with a family history of asthma and this association was stronger in those with asthma onset before 20 years of age. High 25(OH)D levels were associated with lower mean value of FEV1/FVC ratio. No significant association was observed between 25(OH)D levels and other lung function measurements.

CONCLUSION

In this study, 25(OH)D levels below 50 nmol/L were associated with an increased risk of current and ever asthma. Further exploration of this relationship is needed to determine the optimal level of vitamin D in the management of asthma in adolescents and adults.

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.

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.

Regulation of CYP27B1 and CYP24A1 gene expression by recombinant pro-inflammatory cytokines in cultured human trophoblasts

Placenta is an important source of endocrine and immunological factors. During pregnancy, calcitriol, the active metabolite of vitamin D, is also metabolized by decidua and placental tissue by means of CYP27B1 and CYP24A1 for synthesis and inactivation of calcitriol respectively. Calcitriol production is regulated by several factors in a tissue-specific manner. However, the association of pro-inflammatory cytokines on calcitriol metabolism has not been studied in human placenta. The aim of the present study was to investigate the effects of TNF-α, INF-γ, IL-6 and IL-1β upon CYP27B1 and CYP24A1 gene expression in primary cultures of human placental cells. Placentas were obtained immediately after delivery by cesarean section from normotensive women. Cytokine effects upon mRNA of CYPs in enriched trophoblastic cell preparations were evaluated by using qPCR. The results showed that incubation of trophoblasts in the presence of each cytokine resulted in a significant increase of both CYPs expression. Interestingly, TNF-α increased significantly the ratio of CYP24A1/CYP27B1 gene expression, while IFN-γ preferentially induced CYP27B1, whereas IL-1β and IL-6 stimulated gene expression of both CYPs in the same proportion. The results suggest that cytokines among other factors regulate calcitriol metabolism in human placenta; specifically, INF-γ may contribute to calcitriol production while TNF-α favors its catabolism.

The immediate protective response to microbial challenge

The innate immune system detects infection and tissue injury through different families of pattern-recognition receptors (PRRs), such as Toll-like receptors. Most PRR-mediated responses initiate elaborate processes of signaling, transcription, translation, and secretion of effector mediators, which together require time to achieve. Therefore, PRR-mediated processes are not active in the early phases of infection. These considerations raise the question of how the host limits microbial replication and invasion during this critical period. Here, we examine the crucial defense mechanisms, such as antimicrobial peptides or extracellular traps, typically activated within minutes of the initial infection phase, which we term the "immediate protective response". Deficiencies in different components of the immediate protective response are often associated with severe and recurrent infectious diseases in humans, highlighting their physiologic importance.

Cigarette smoke exposure is associated with vitamin D3 deficiencies in patients with chronic rhinosinusitis

BACKGROUND

Cigarette smoke (CS) plays a role in the exacerbation of chronic rhinosinusitis (CRS); however, the mechanism for this is unknown. We hypothesize that CS impairs human sinonasal epithelial cell (HSNEC) conversion of 25(OH)D3 (25VD3) to 1,25-dihydroxyvitamin D3 (1,25VD3) and, furthermore, that supplementation with 1,25VD3 will reverse smoke-induced inflammatory responses by HSNECs.

OBJECTIVE

We sought to determine the effect of CS on vitamin D3 (VD3) levels, conversion, and regulation of CS-induced inflammation in control subjects and patients with CRS.

METHODS

Blood and sinus tissue explants were collected at the time of surgery from control subjects, patients with chronic rhinosinusitis without nasal polyps, and patients with chronic sinusitis with nasal polyps (CRSwNP). Expression of VD3 metabolizing enzymes were measured by using RT-PCR. Primary HSNECs were cultured from tissue explants. 25VD3 with and without cigarette smoke extract (CSE) was used to examine conversion of 25VD3 to 1,25VD3, as well as HSNEC production of proinflammatory cytokines.

RESULTS

CS exposure was associated with reduced circulating and sinonasal 25VD3 levels in all groups compared with those seen in CS-naive, disease-matched counterparts. CS exposure decreased expression of CYP27B1 and was especially pronounced in patients with CRSwNP. CSE impairs control HSNEC conversion of 25VD3. HSNECs from patients with CRSwNP also demonstrate an intrinsic reduction in conversion of 25VD3 to 1,25VD3. Exogenous 1,25VD3 reduces CSE-induced cytokine production by HSNECs.

CONCLUSIONS

Exposure to CS is associated with reduced 25VD3 levels and an impaired ability of HSNECs to convert 25VD3 to 1,25VD3. Addition of 1,25VD3 reduces the proinflammatory effects of CS on HSNECs. Impaired VD3 conversion by CS exposure represents a novel mechanism through which CS induces its proinflammatory effects.

Beneficial role of vitamin D3 in the prevention of certain respiratory diseases

There is evidence of aberrations in the vitamin D-endocrine system in subjects with respiratory diseases. Vitamin D deficiency is highly prevalent in patients with respiratory diseases, and patients who receive vitamin D have significantly larger improvements in inspiratory muscle strength and maximal oxygen uptake. Studies have provided an opportunity to determine which proteins link vitamin D to respiratory pathology, including the major histocompatibility complex class II molecules, vitamin D receptor, vitamin D-binding protein, chromosome P450, Toll-like receptors, poly(ADP-ribose) polymerase-1, and the reduced form of nicotinamide adenine dinucleotide phosphate. Vitamin D also exerts its effect on respiratory diseases through cell signaling mechanisms, including matrix metalloproteinases, mitogen-activated protein kinase pathways, the Wnt/β-catenin signaling pathway, prostaglandins, reactive oxygen species, and nitric oxide synthase. In conclusion, vitamin D plays a significant role in respiratory diseases. The best form of vitamin D for use in the treatment of respiratory diseases is calcitriol because it is the active metabolite of vitamin D3 and modulates inflammatory cytokine expression. Further investigation of calcitriol in respiratory diseases is needed.

Bone and vitamin D metabolism in HIV

Human immunodeficiency virus (HIV) infection has progressed to a chronic disease and HIV positive individuals are living longer lives. This has lead to an increase in morbidity and mortality due to secondary issues, one being HIV bone disease. HIV infected pediatric and adult populations have a greater incidence in reduction of BMD as compared to the controls. Osteoporosis has been reported to be present in up to 15 % of HIV positive patients. We are starting to understand the mechanism behind the changes in HIV bone disease. Viral proteins interfere with osteoblastic activity either by direct interaction or by the inflammatory process that they induce. Anti-viral management, including highly active antiretroviral therapy (HAART), protease inhibitors, and nucleoside/nucleotide reverse transcriptase inhibitors (NRTI) also are involved in disrupting proper bone metabolism. Vitamin D levels have strong correlation with bone disease in HIV patients, and are dependent not only to chronic disease state, but interaction of pharmacologic management and inflammatory process as well. Work up of the secondary causes of osteopenia and osteoporosis should be undertaken in all patients. DEXA scan is recommended in all post-menopausal women with HIV, all HIV infected men 50 years of age or older and in those with a history of fragility fractures regardless of age or gender. Preventive measures include adequate nutrition, calcium and Vitamin D intake daily, muscle strengthening and balance exercises to increase BMD and reduce fractures. Bisphosphonates are considered to be the first line for the treatment of HIV associated bone disease. This review will describe how the balanced mechanism of bone metabolism is interrupted by the HIV infection itself, the complications that arise from HIV/AIDS, and its treatment options.

Cell-Type Specific Determinants of NRAMP1 Expression in Professional Phagocytes

The Natural resistance-associated macrophage protein 1 (Nramp1 or Solute carrier 11 member 1, Slc11a1) transports divalent metals across the membrane of late endosomes and lysosomes in professional phagocytes. Nramp1 represents an ancient eukaryotic cell-autonomous defense whereas the gene duplication that yielded Nramp1 and Nramp2 predated the origin of Sarcopterygians (lobe-finned fishes and tetrapods). SLC11A1 genetic polymorphisms associated with human resistance to tuberculosis consist of potential regulatory variants. Herein, current knowledge of the regulation of SLC11A1 gene expression is reviewed and comprehensive analysis of ENCODE data available for hematopoietic cell-types suggests a hypothesis for the regulation of SLC11A1 expression during myeloid development and phagocyte functional polarization. SLC11A1 is part of a 34.6 kb CTCF-insulated locus scattered with predicted regulatory elements: a 3' enhancer, a large 5' enhancer domain and four elements spread around the transcription start site (TSS), including several C/EBP and PU.1 sites. SLC11A1 locus ends appear mobilized by ETS-related factors early during myelopoiesis; activation of both 5' and 3' enhancers in myelo-monocytic cells correlate with transcription factor binding at the TSS. Characterizing the corresponding cis/trans determinants functionally will establish the mechanisms involved and possibly reveal genetic variation that impacts susceptibility to infectious or immune diseases.