Calcium and 1 alpha,25-dihydroxyvitamin D3 target the TNF-alpha pathway to suppress experimental inflammatory bowel disease

Common variation in the vitamin D receptor gene and risk of inflammatory bowel disease in an Irish case-control study

OBJECTIVE

Vitamin D may protect against the development of inflammatory bowel disease (IBD). Several preliminary studies in separate geographical locations suggest that these effects may be partly mediated by genetic variants of the vitamin D receptor (VDR). The data, however, are yet to be confirmed in large European cohorts. This study aimed to determine if common VDR polymorphisms affected IBD risk in an Irish population.

MATERIALS AND METHODS

The study was based on a cohort of 1359 Irish participants. Frequencies of the common VDR gene polymorphisms rs2228570 (FokI), rs1544410 (BsmI), rs7975232 (ApaI), and rs731236 (TaqI) were determined using allele-specific PCR in a case-control analysis of 660 patients with IBD and 699 controls. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between these variants and risk of IBD.

RESULTS

There was no statistically significant effect observed on IBD risk for any of the four VDR polymorphisms tested. Furthermore, no significant differences were observed in susceptibility when the population was stratified by sex or IBD subtype (Crohn's disease or ulcerative colitis). Notably, however, there was an increased risk observed for both IBD and ulcerative colitis associated with heterozygote carriage of the FokI allele that approached significance (OR=1.21, 95% CI=0.95-1.53, P=0.12 and OR=1.36, 95% CI=0.98-1.89, P=0.06, respectively), this merits further investigation.

CONCLUSION

This study indicates that there is no major effect for common variation in the VDR gene alone on predisposition to IBD in the Irish population.

Resveratrol and vitamin D: significant potential interpretative problems arising from their mutual processes, interactions and effects

The hypothesis is formulated and presented that resveratrol and vitamin D have important mutual processes, interactions and induced effects that if not taken into account could seriously jeopardize the interpretation of their current and future preclinical, epidemiological and clinical studies. In support of this hypothesis, evidence is presented that resveratrol and vitamin D mutually share some of the same biochemical processes and mechanisms as well as the fact that they can each affect some of the same diseases and maladies.

Vitamin D and inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) are the main forms of inflammatory bowel disease (IBD), chronic relapsing-remitting inflammatory conditions of uncertain origin affecting the gastrointestinal tract. Much effort has recently been made both in defining the mechanisms underlying the development of IBD, and in broadening the spectrum of effective treatment. Substantial progress has been made in characterising immune-cell populations and inflammatory mediators in IBD. 1,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], the bioactive form of Vitamin D(3), besides having well-known control findings of calcium and phosphorus metabolism, bone formation and mineralization, also has a role in the maintenance of immune- omeostasis. The immune-regulatory role of vitamin D affects both the innate and adaptive immune system contributing to the immune-tolerance of self-structures. Impaired vitamin D supply/regulation, amongst other factors, leads to the development of autoimmune processes in animal models of various autoimmune diseases, including IBD. The administration of vitamin D in these animals leads to improvement of immune-mediated symptoms. Future studies now need to focus on the potential of vitamin D and its derivatives as therapeutic adjuncts in the treatment of IBD.

Vitamin D deficiency reduces the benefits of progesterone treatment after brain injury in aged rats

Administration of the neurosteroid progesterone (PROG) has been shown to be beneficial in a number of brain injury models and in two recent clinical trials. Given widespread vitamin D deficiency and increasing traumatic brain injuries (TBIs) in the elderly, we investigated the interaction of vitamin D deficiency and PROG with cortical contusion injury in aged rats. Vitamin D deficient (VitD-deficient) animals showed elevated inflammatory proteins (TNFα, IL-1β, IL-6, NFκB p65) in the brain even without injury. VitD-deficient rats with TBI, whether given PROG or vehicle, showed increased inflammation and greater open-field behavioral deficits compared to VitD-normal animals. Although PROG was beneficial in injured VitD-normal animals, in VitD-deficient subjects neurosteroid treatment conferred no improvement over vehicle. A supplemental dose of 1,25-dihydroxyvitamin D(3) (VDH) given with the first PROG treatment dramatically improved results in VitD-deficient rats, but treatment with VDH alone did not. Our results suggest that VitD-deficiency can increase baseline brain inflammation, exacerbate the effects of TBI, and attenuate the benefits of PROG treatment; these effects may be reversed if the deficiency is corrected.

Vitamin D, disease and therapeutic opportunities

The discovery of the vitamin D endocrine system and a receptor for the hormonal form, 1α,25-dihydroxyvitamin D(3), has brought a new understanding of the relationship between vitamin D and metabolic bone diseases, and has also established the functions of vitamin D beyond the skeleton. This has ushered in many investigations into the possible roles of vitamin D in autoimmune diseases, cardiovascular disorders, infectious diseases, cancers and granuloma-forming diseases. This article presents an evaluation of the possible roles of vitamin D in these diseases. The potential of vitamin D-based therapies in treating diseases for which the evidence is most compelling is also discussed.

Vitamin D and gastrointestinal diseases: inflammatory bowel disease and colorectal cancer

Over the past 5 years, there has been a rapid resurgence of interest in vitamin D outside of its traditional role in metabolic bone disease. Some nontraditional roles ascribed to vitamin D include anti-inflammatory and immune-modulating effects. These effects have led to possible implications in the pathophysiology of immune-mediated diseases including multiple sclerosis and inflammatory bowel disease (IBD). In addition, vitamin D insufficiency has been linked to higher rates of cancers including colon, prostate and breast cancers. Given these diverse associations of vitamin D and disease states, this review describes recent advances with regard to vitamin D and gastrointestinal diseases, in particular IBD and colorectal cancer.

Vitamin D and cardiometabolic health: a review of the evidence

The cardiometabolic syndrome (MetS) is a clustering of related metabolic abnormalities including abdominal adiposity, insulin resistance, hypertension, dyslipidaemia and increased inflammatory and thrombotic markers, which is linked to increased risk of type 2 diabetes, CVD and overall mortality. Several cross-sectional and prospective studies have shown an association between low vitamin D status, as indicated by concentrations of serum 25-hydroxyvitamin D (s25(OH)D), and increased prevalence of the MetS and individual CVD risk factors. These epidemiological observations are supported by mechanistic studies but experimental data are limited. The available data from intervention studies are largely confounded as most vitamin D supplementation trials were mainly carried out to explore the role of Ca in CVD and include Ca in the treatment arms. Inadequate consideration of seasonal effects on s25(OH)D concentrations is also a common design flaw in most studies. Further complications arise from shared risk factors such as adiposity and ageing, which predispose individuals to exhibit both a more pronounced risk profile and relatively lower s25(OH)D concentrations. In conclusion, while epidemiological associations are promising and a rationale for low vitamin D status as a potentially modifiable risk factor for CVD is supported by mechanistic data, suitable experimental data from appropriately designed trials are just beginning to emerge. As yet, this body of literature is too immature to draw firm conclusions on the role of vitamin D in CVD prevention. Carefully controlled vitamin D trials in well-described population groups using intervention doses that are titrated against target s25(OH)D concentrations could yield potentially valuable outcomes that may have a positive impact on CVD risk modification.

[Effect of vitamin D deficiency on cardiovascular risk]

Vitamin D deficiency affects almost 50 % of the population worldwide. Besides its classical effects on bone and calcium metabolism, vitamin D displays a wide spectrum of non classical effects. Among these effects, those targeting the cardiovascular system are mostly documented by observational, experimental and small intervention trials that most often evaluated intermediate parameters. The time has now come for large placebo-controlled trials targeting clinical endpoints such as the incidence of major cardiovascular events and mortality.

Vitamin D and bone health: potential mechanisms

Osteoporosis is associated with increased morbidity, mortality and significant economic and health costs. Vitamin D is a secosteriod hormone essential for calcium absorption and bone mineralization which is positively associated with bone mineral density [BMD]. It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. Sub-optimal vitamin D status has been reported in many populations but it is a particular concern in older people; thus there is clearly a need for effective strategies to optimise bone health. A number of recent studies have suggested that the role of vitamin D in preventing fractures may be via its mediating effects on muscle function (a defect in muscle function is one of the classical signs of rickets) and inflammation. Studies have demonstrated that vitamin D supplementation can improve muscle strength which in turn contributes to a decrease in incidence of falls, one of the largest contributors to fracture incidence. Osteoporosis is often considered to be an inflammatory condition and pro-inflammatory cytokines have been associated with increased bone metabolism. The immunoregulatory mechanisms of vitamin D may thus modulate the effect of these cytokines on bone health and subsequent fracture risk. Vitamin D, therefore, may influence fracture risk via a number of different mechanisms.

Effects of low-fat dairy consumption on markers of low-grade systemic inflammation and endothelial function in overweight and obese subjects: an intervention study

Although increased concentrations of plasma inflammatory markers are not one of the criteria to diagnose the metabolic syndrome, low-grade systemic inflammation is receiving large attention as a metabolic syndrome component and cardiovascular risk factor. As several epidemiological studies have suggested a negative relationship between low-fat dairy consumption and the metabolic syndrome, we decided to investigate the effects of low-fat dairy consumption on inflammatory markers and adhesion molecules in overweight and obese subjects in an intervention study. Thirty-five healthy subjects (BMI>27 kg/m2) consumed, in a random order, low-fat dairy products (500 ml low-fat milk and 150 g low-fat yogurt) or carbohydrate-rich control products (600 ml fruit juice and three fruit biscuits) daily for 8 weeks. Plasma concentrations of TNF-α were decreased by 0·16 (sd 0·50) pg/ml (P = 0·070), and soluble TNF-α receptor-1 (s-TNFR-1) was increased by 110·0 (sd 338·4) pg/ml (P = 0·062) after the low-fat dairy period than after the control period. s-TNFR-2 was increased by 227·0 (sd 449·0) pg/ml (P = 0·020) by the dairy intervention. As a result, the TNF-α index, defined as the TNF-α:s-TNFR-2 ratio, was decreased by 0·000053 (sd 0·00 012) (P = 0·015) after the dairy diet consumption. Low-fat dairy consumption had no effect on IL-6, monocyte chemoattractant protein-1, intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 concentrations. The present results indicate that in overweight and obese subjects, low-fat dairy consumption for 8 weeks may increase concentrations of s-TNFR compared with carbohydrate-rich product consumption, but that it has no effects on other markers of chronic inflammation and endothelial function.

Primary prevention of colorectal cancer

Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.

Role of nutrients in the development of neonatal immune response

Nutrients exert unique regulatory effects in the perinatal period that mold the developing immune system. The interactions of micronutrients and microbial and environmental antigens condition the post-birth maturation of the immune system, influencing reactions to allergens, fostering tolerance towards the emerging gastrointestinal flora and ingested antigens, and defining patterns of host defense against potential pathogens. The shared molecular structures that are present on microbes or certain plants, but not expressed by human cells, are recognized by neonatal innate immune receptors. Exposure to these activators in the environment through dietary intake in early life can modify the immune response to allergens and prime the adaptive immune response towards pathogens that express the corresponding molecular structures.

Genetic variation in the vitamin D receptor (VDR) and the vitamin D-binding protein (GC) and risk for colorectal cancer: results from the Colon Cancer Family Registry

Epidemiologic evidence supports a role for vitamin D in colorectal cancer (CRC) risk. Variants in vitamin D-related genes might modify the association between vitamin D levels and CRC risk. In this analysis, we did a comprehensive evaluation of common variants in the vitamin D receptor (VDR) and the vitamin D-binding protein (GC; group-specific component) genes using a population-based case-unaffected sibling control design that included 1,750 sibships recruited into the Colon Cancer Family Registry. We also evaluated whether any associations differed by calcium supplement use, family history of CRC, or tumor characteristics. Heterogeneity by calcium and vitamin D intake was evaluated for a subset of 585 cases and 837 sibling controls who completed a detailed food frequency questionnaire. Age- and sex-adjusted associations were estimated using conditional logistic regression. Overall, we did not find evidence for an association between any single-nucleotide polymorphism (SNP) in VDR or GC and risk for CRC (range of unadjusted P values 0.01-0.98 for VDR and 0.07-0.95 for GC). None of these associations was significant after adjustment for multiple comparisons. We also found no evidence that calcium or vitamin D intake (food and supplement) from the food frequency questionnaire modified the association estimates between VDR and GC SNPs and CRC. We did observe associations between SNPs in GC and microsatellite unstable CRC, although these results should be confirmed in additional studies. Overall, our results do not provide evidence for a role of common genetic variants in VDR or GC in susceptibility to CRC.

Vitamin D and calcium insufficiency-related chronic diseases: molecular and cellular pathophysiology

A compromised vitamin D status, characterized by low 25-hydroxyvitamin D (25-(OH)D) serum levels, and a nutritional calcium deficit are widely encountered in European and North American countries, independent of age or gender. Both conditions are linked to the pathogenesis of many degenerative, malignant, inflammatory and metabolic diseases. Studies on tissue-specific expression and activity of vitamin D metabolizing enzymes, 25-(OH)D-1 alpha-hydroxylase and 25-(OH)D-24-hydroxylase, and of the extracellular calcium-sensing receptor (CaR) have led to the understanding of how, in non-renal tissues and cellular systems, locally produced 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) and extracellular Ca(2+) act jointly as key regulators of cellular proliferation, differentiation and function. Impairment of cooperative signalling from the 1,25-(OH)(2)D(3)-activated vitamin D receptor (VDR) and from the CaR in vitamin D and calcium insufficiency causes cellular dysfunction in many organs and biological systems, and, therefore, increases the risk of diseases, particularly of osteoporosis, colorectal and breast cancer, inflammatory bowel disease, insulin-dependent diabetes mellitus type I, metabolic syndrome, diabetes mellitus type II, hypertension and cardiovascular disease. Understanding the underlying molecular and cellular processes provides a rationale for advocating adequate intake of vitamin D and calcium in all populations, thereby preventing many chronic diseases worldwide.

Supplemental calcium attenuates the colitis-related increase in diarrhea, intestinal permeability, and extracellular matrix breakdown in HLA-B27 transgenic rats

We have shown in several controlled rat and human infection studies that dietary calcium improves intestinal resistance and strengthens the mucosal barrier. Reinforcement of gut barrier function may alleviate inflammatory bowel disease (IBD). Therefore, we investigated the effect of supplemental calcium on spontaneous colitis development in an experimental rat model of IBD. HLA-B27 transgenic rats were fed a purified high-fat diet containing either a low or high calcium concentration (30 and 120 mmol CaHPO4/kg diet, respectively) for almost 7 wk. Inert chromium EDTA (CrEDTA) was added to the diets to quantify intestinal permeability by measuring urinary CrEDTA excretion. Relative fecal wet weight was determined to quantify diarrhea. Colonic inflammation was determined histologically and by measuring mucosal interleukin (IL)-1beta. In addition, colonic mucosal gene expression of individual rats was analyzed using whole-genome microarrays. The calcium diet significantly inhibited the increase in intestinal permeability and diarrhea with time in HLA-B27 rats developing colitis compared with the control transgenic rats. Mucosal IL-1beta levels were lower in calcium-fed rats and histological colitis scores tended to be lower (P = 0.08). Supplemental calcium prevented the colitis-induced increase in the expression of extracellular matrix remodeling genes (e.g. matrix metalloproteinases, procollagens, and fibronectin), which was confirmed by quantitative real-time PCR and gelatin zymography. In conclusion, dietary calcium ameliorates several important aspects of colitis severity in HLA-B27 transgenic rats. Reduction of mucosal irritation by luminal components might be part of the mechanism. These results show promise for supplemental calcium as effective adjunct therapy for IBD.

Combination treatment with progesterone and vitamin D hormone may be more effective than monotherapy for nervous system injury and disease

More than two decades of pre-clinical research and two recent clinical trials have shown that progesterone (PROG) and its metabolites exert beneficial effects after traumatic brain injury (TBI) through a number of metabolic and physiological pathways that can reduce damage in many different tissues and organ systems. Emerging data on 1,25-dihydroxyvitamin D(3) (VDH), itself a steroid hormone, have begun to provide evidence that, like PROG, it too is neuroprotective, although some of its actions may involve different pathways. Both agents have high safety profiles, act on many different injury and pathological mechanisms, and are clinically relevant, easy to administer, and inexpensive. Furthermore, vitamin D deficiency is prevalent in a large segment of the population, especially the elderly and institutionalized, and can significantly affect recovery after CNS injury. The combination of PROG and VDH in pre-clinical and clinical studies is a novel and compelling approach to TBI treatment.

C-reactive protein and fibrinogen of bedridden older patients in a six-month vitamin D supplementation trial

OBJECTIVE

To elucidate the association between vitamin D status, C-reactive protein (CRP) and fibrinogen.

DESIGN

Secondary analysis of a randomised double-blind placebo controlled trial.

SETTING

Four longterm care hospitals (1215 beds) in Helsinki, Finland.

PARTICIPANTS

218 long-term inpatients aged over 65 years.

INTERVENTION

Eligible patients (n = 218) were randomized to receive 0 IU/d, 400 IU/d, or 1200 IU/d cholecalciferol for six months.

METHODS

Plasma 25-hydroxyvitamin D (25-OHD), parathyroid hormone (PTH), high sensitive CRP, fibrinogen, amino-terminal propeptide of type I procollagen (PINP), and carboxy-terminal telopeptide of type I collagen (ICTP) were measured.

RESULTS

The patients were aged (84.5 +/- 7.5 years), vitamin D deficient (25-OHD = 23 +/- 10 nmol/l), chronically bedridden and in stable general condition. The mean baseline CRP and fibrinogen were 10.86 mg/l (0.12 mg/l - 125.00 mg/l) and 4,7 g/l (2.3 g/l - 8.6 g/l), respectively. CRP correlated with ICTP (r = 0.217, p = 0.001), but not with vitamin D status. Supplementation significantly increased 25-OHD concentrations, but the changes in CRP and fibrinogen were insignificant and inconsistent. The post-trial CRP concentrations (0.23 mg/l -138.00 mg/l) correlated with ICTP (r = 0.156, p < 0.001), but no association was found with vitamin D status. The baseline and post-trial fibrinogen correlated with CRP, only.

CONCLUSIONS

CRP concentrations are associated with bone turnover, but not with vitamin D status, and vitamin D supplementation has no major effect on CRP or fibrinogen concentrations in bedridden older patients.

Drug-induced hypersensitivity syndrome: clinical and biologic disease patterns in 24 patients

Drug-induced hypersensitivity syndrome (DIHS), also called drug rash with eosinophilia and systemic symptoms (DRESS), is a severe reaction usually characterized by fever, rash, and multiorgan failure, occurring 1-8 weeks after drug introduction. It is an immune-mediated reaction involving macrophage and T-lymphocyte activation and cytokine release, although no consensus has been reached as to its etiology. The skin, hematopoietic system, and liver are frequently involved. DIHS can mimic severe sepsis, viral infection, adult-onset Still disease (AOSD), or lymphoproliferation.We describe 24 consecutive patients with DIHS who were hospitalized between September 2004 and March 2008. Criteria for inclusion in this observational study were suspected drug reaction, eosinophilia >or=500/microL and/or atypical lymphocytes, involvement of at least 2 organs (skin being 1 of them), with suggestive chronology and exclusion of other diagnoses. Our cohort of 12 women and 12 men had a median age of 49 years (range, 22-82 yr), and 11 had skin phototype V or VI. Patients with mild or no rash were immunocompromised (7/24)- defined as treatment with prednisone (>or=10 mg/d) and another immunosuppressant drug, or human immunodeficiency virus infection. All patients were febrile (>38 degrees C), 14 had localized or generalized edema, 7 had pharyngitis, 8 had lymphadenopathy, 22 had hepatitis, 4 had nephritis, 2 had noninfectious and nonlithiasic angiocholitis or cholecystitis. Ten patients were hypotensive, 5 of whom had associated laboratory signs and/or imaging findings suggestive of acute myocardial dysfunction. Half of the patients had hemogram abnormalities, including eosinophilia. Nine DIHS patients fulfilled the Fautrel criteria for AOSD diagnosis, including glycosylated ferritin <20% in 4/11, with or without laboratory characteristics of hemophagocytosis. Twenty DIHS episodes occurred during the less sunny months of October to March.We determined 25-hydroxyvitamin D3 (25[OH]D3) levels in 18 patients and found that 9 patients had vitamin D deficiency (<25 nmol/L or <10 microg/L) and 5 had vitamin D insufficiency (25-50 nmol/L). Moreover, 25(OH)D3 levels were inversely correlated with ferritin values. After culprit-drug withdrawal, outcomes were favorable for all patients, including those with cardiac abnormalities under slow tapering of glucocorticoids.We recommend looking for the frequent but underdiagnosed hypersensitivity myocarditis with noninvasive diagnostic tools, such as N-terminal probrain natriuretic peptide, and promptly withdrawing the culprit drug and starting glucocorticoids. Vitamin D deficiency might be a DIHS risk or severity factor, especially for patients with high skin phototype and during the winter. Because DIHS clinical and laboratory patterns share similarities with AOSD and hemophagocytosis, DIHS should be included in their differential diagnoses.

Potential for vitamin D receptor agonists in the treatment of cardiovascular disease

Vitamin D(3) is made in the skin and modified in the liver and kidney to form the active metabolite, 1,25-dihydroxyvitamin D(3) (calcitriol). Calcitriol binds to a nuclear receptor, the vitamin D receptor (VDR), and activates VDR to recruit cofactors to form a transcriptional complex that binds to vitamin D response elements in the promoter region of target genes. During the past three decades the field has focused mainly on the role of VDR in the regulation of parathyroid hormone, intestinal calcium/phosphate absorption and bone metabolism; several VDR agonists (VDRAs) have been developed for the treatment of osteoporosis, psoriasis and hyperparathyroidism secondary to chronic kidney disease (CKD). Emerging evidence suggests that VDR plays important roles in modulating cardiovascular, immunological, metabolic and other functions. For example, data from epidemiological, preclinical and clinical studies have shown that vitamin D and/or 25(OH)D deficiency is associated with increased risk for cardiovascular disease (CVD). However, VDRA therapy seems more effective than native vitamin D supplementation in modulating CVD risk factors. In CKD, where decreasing VDR activation persists over the course of the disease and a majority of the patients die of CVD, VDRA therapy was found to provide a survival benefit in both pre-dialysis and dialysis CKD patients. Although VDR plays an important role in regulating cardiovascular function and VDRAs may be potentially useful for treating CVD, at present no VDRA is approved for CVD, and also no serum markers, beside parathyroid hormone in CKD, exist to indicate the efficacy of VDRA in CVD.

Immunomodulatory effects of 1,25-dihydroxyvitamin D3 on TH1/TH2 cytokines in inflammatory bowel disease: an in vitro study

Crohn's disease (CD) is associated with a higher type-1-helper T cell (Th1) cytokine expression, whereas ulcerative colitis (UC) appears to express a modified Th2 response. In addition to its classic role in calcium homeostasis, calcitriol, the hormonal active form of vitamin D, exerts immunoregulatory effects such as modulation of Th1/Th2 cytokines. Therefore, calcitriol administration could modify immune dysfunction in CD and UC. Nine patients with UC (M/F: 5/4; mean age 47 years, remission(R)/active(A) disease: 7/2), 8 patients with CD (M/F: 2/6; mean age 36, R/A 5/3) and 6 healthy controls (HC) (M/F: 3/3, mean age 4) were enrolled. Peripheral blood was collected after a drug-washout of 15 days and peripheral blood mononuclear cells were stimulated with mitogens alone or in the presence of physiological concentrations of calcitriol (100 pg/ml). Type 1 (IL-2, TNF-alpha, IFN-gamma) and type 2 (IL-10) cytokine production was assayed on supernatants by ELISA. Compared to HC, TNF-alpha production was significantly higher both in UC (p=0.0002) and CD (p=0.0001) patients, at baseline and after incubation with calcitriol (UC p=0.0003, CD p=0.0009). The effects of calcitriol incubation were: 1) reduced IFN-gamma (p=0.024) and increased IL-10 (p=0.06) production in UC patients; 2) reduced TNF-alpha production in CD (p=0.032); 3) no significant effects in HC. Calcitriol increased, albeit not significantly, IL-10 production in UC compared to CD patients (p=0.09). These results suggest an important modulatory role of vitamin D in the Th1/Th2 immune response. The observation that the effect of this modulation was different in CD compared to UC patients provides an interesting area of research into the pathogenesis and treatment of these inflammatory conditions.

Symposium on 'The challenge of translating nutrition research into public health nutrition'. Session 3: Joint Nutrition Society and Irish Nutrition and Dietetic Institute Symposium on 'Nutrition and autoimmune disease'. Nutrition in Crohn's disease

The exact aetiology of Crohn's disease remains unknown. The consensus is that the disease results from a complex interaction between genes, immunity and environmental factors. Diet is attractive, in theory, as an environmental risk factor in the aetiology of the disease. The epidemiological data, often impeded by methodological issues, have failed to confirm a direct link between pre-diet illness and the development of Crohn's disease. Once diagnosed, however, nutrition has an important role in disease management. Among the nutritional issues are malnutrition, weight loss and suboptimal nutritional status; these outcomes may be present at any stage of the disease but are likely to be overt during acute illness and hospitalisation. Malnutrition has been identified in approximately 40% of hospital admissions with Crohn's disease and is associated with higher mortality, longer hospital stays and higher healthcare costs. Patients in remission may indeed be overweight and appear to be influenced by the general population trends toward overweight and obesity. Irrespective of BMI, patients are at risk of micronutrient deficiencies. Vitamin D deficiency, for example, is common in Crohn's disease and has important implications for bone health. Moreover, newer evidence suggests that vitamin D has potential anti-inflammatory effects. Dietary approaches, in the form of enteral nutrition, have previously been shown to reduce inflammation and treat the active disease. Current guidelines now recommend that corticosteroids are more effective than enteral nutrition for treating adults. Enteral nutrition has important growth and developmental benefits and continues to be a recommended therapy for children with Crohn's disease.

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

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

Nutritional calcium modulates colonic expression of vitamin D receptor and pregnane X receptor target genes

Low nutritional calcium contributes to disruption of the intestinal epithelial barrier function, to hyperproliferation of colonocytes and increased occurrence of aggressive secondary bile acids in the gut lumen. These mechanisms are also known to be involved in the etiology of colonic inflammation and cancer. We studied in mice and human adenocarcinoma-derived Caco-2 cells the impact of low calcium on markers of inflammation (cyclooxygenase-2; COX-2), of detoxification (pregnane and xenobiotic receptor (PXR)/steroid and xenobiotic receptor (SXR), cytochrome P450 steroid-inducible 3a11 (CYP3A11)), and on expression of the vitamin D system as a protection against tumorigenesis. Caco-2 cells express high COX-2 and low SXR mRNA levels when subconfluent. During differentiation this is reversed, while low calcium enhanced COX-2 protein expression. In vivo low dietary calcium significantly increased the expression of the PXR target gene CYP3A11 in the proximal colon, suggesting compensatory defense mechanisms. In comparison with males, low nutritional calcium elicits a better protective response in females: both the vitamin D synthesizing 25-hydroxyvitamin D(3 )1alpha hydroxylase (CYP27B1) mRNA and the detoxifying CYP3A11 mRNA are augmented more. While it is recognized that colonic vitamin D synthesis may prevent tumor progression, low dietary calcium also elevates the 1,25-(OH)(2)-D(3) catabolic 25-hydroxyvitamin D(3) 24 hydroxylase (CYP24) expression primarily in the proximal colon. Our data suggest the proximal colon as the primary site of response to insufficient calcium intake.

Advances in vitamin D and inflammatory bowel disease

In respect of the comprehensive effect in immunologic regulation (on innate immunity and adaptive immunity) and antibacterial activity, vitamin D is in a high profile position in recent years. Despite the uncertain mechanism, it is a common sense that commensal enteric microbiota initiate and perpetuate immune-mediated bowel inflammation. This suggests that there may be a link between vitamin D's function and pathogenesis of inflammatory bowel disease, and vitamin D-associated agents may be prospective for treatment of inflammatory bowel disease.

Serum tumor necrosis factor-alpha concentrations are negatively correlated with serum 25(OH)D concentrations in healthy women

Background

Circulating 25 hydroxyvitamin D (25 (OH)D), an accurate measure of vitamin D status, is markedly greater in individuals with increased exposure to ultraviolet B (UVB) light via sunlight or the use of artificial UV light. Aside from the known relationship between vitamin D and bone, vitamin D has also been implicated in immune function and inflammation. Furthermore, a mass of evidence is accumulating that vitamin D deficiency could lead to immune malfunction. Our overall objective was to study the relationship between vitamin D status (as determined by serum 25(OH) D concentrations) and inflammatory markers in healthy women.

Methods

This observational study included 69 healthy women, age 25–82 years. Women with high UVB exposure and women with minimal UVB exposure were specifically recruited to obtain a wide-range of serum 25(OH)D concentrations. Health, sun exposure and habitual dietary intake information were obtained from all subjects. Body composition was determined by dual-energy-x-ray absorptiometry. A fasting blood sample was collected in the morning and analyzed for serum 25(OH)D, parathyroid hormone (iPTH), estradiol (E₂), cortisol, and inflammatory markers [tumor necrosis factor -alpha (TNF-α), interleukin-6 and -10 (IL-6, IL-10), and C-reactive protein (CRP)].

Results

Women with regular UVB exposure (Hi-D) had serum 25(OH)D concentrations that were significantly higher (p < 0.0001) and iPTH concentrations that were significantly lower (p < 0.0001) than women without regular UVB exposure (Lo-D). Although IL-6, IL-10, and CRP did not have a statistically significant relationship with 25(OH)D concentrations, linear regression models revealed a significant inverse relationship between serum 25(OH)D and TNF-α concentrations. This relationship remained significant after controlling for potential covariates such as body fat mass, menopausal status, age, or hormonal contraceptive use.

Conclusion

Serum 25(OH)D status is inversely related to TNF-α concentrations in healthy women, which may in part explain this vitamin's role in the prevention and treatment of inflammatory diseases. Results gleaned from this investigation also support the need to re-examine the biological basis for determining optimal vitamin D status.

Control of autoimmune diseases by the vitamin D endocrine system

1,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], the biologically active form of vitamin D(3), is a secosteroid hormone essential for bone and mineral homeostasis. It regulates the growth and differentiation of multiple cell types, and displays immunoregulatory and anti-inflammatory properties. Cells involved in innate and adaptive immune responses--including macrophages, dendritic cells, T cells and B cells--express the vitamin D receptor (VDR), and can both produce and respond to 1,25(OH)(2)D(3). The net effect of the vitamin D system on the immune response is an enhancement of innate immunity coupled with multifaceted regulation of adaptive immunity. Epidemiological evidence indicates a significant association between vitamin D deficiency and an increased incidence of several autoimmune diseases, and clarification of the physiological role of endogenous VDR agonists in the regulation of autoimmune responses will guide the development of pharmacological VDR agonists for use in the clinic. The antiproliferative, prodifferentiative, antibacterial, immunomodulatory and anti-inflammatory properties of synthetic VDR agonists could be exploited to treat a variety of autoimmune diseases, from rheumatoid arthritis to systemic lupus erythematosus, and possibly also multiple sclerosis, type 1 diabetes, inflammatory bowel diseases, and autoimmune prostatitis.

Murine TNF(DeltaARE) Crohn's disease model displays diminished expression of intestinal Ca2+ transporters

BACKGROUND

Patients suffering from Crohn's disease (CD) show increased incidence of low bone mineral density. Investigating this complication is difficult because the exact etiology of CD remains elusive. Mice carrying a deletion in the tumor necrosis factor (TNF) AU-rich elements (ARE) are reported as a model for human CD and are characterized by elevated TNF-alpha levels and inflammations in the terminal ileum. To evaluate whether these mice have a Ca(2+) handling problem, this study analyzed the Ca(2+) homeostasis in heterozygous TNF(DeltaARE) mice (TNF(DeltaARE/+)) in comparison to wildtype littermates.

METHODS

Beside serum Ca(2+) and vitamin D levels, the expression of Ca(2+) transporters was analyzed in intestine, kidney and bone using quantitative real-time PCR, Western blot and immunohistochemistry. Bone scans were performed to measure bone parameters.

RESULTS

Ca(2+) transporters in duodenum (TRPV6, calbindin-D(9K), PMCA1b) and kidney (TRPV5, calbindin-D(28K), NCX1) showed significantly reduced mRNA expression levels in TNP(DeltaARE/+) mice, except for renal TRPV5. In bone, only calbindin-D(9K) mRNA displayed a significant down-regulation. These findings were supported by declined duodenal calbindin-D(9K) and renal calbindin-D(28K) protein values. Likely, this down-regulation of Ca(2+) transporters in TNP(DeltaARE/+) mice is mediated by the 58 +/- 9% reduction in serum 1,25(OH)(2)D(3) levels. Diminished expression of Ca(2+) transporters combined with unchanged serum Ca(2+) levels assumes Ca(2+) loss from bone to compensate for the body's overall Ca(2+) shortage. Indeed, microcomputed tomography scanning demonstrated reduced trabecular and corticol bone thickness and volume in TNF(DeltaARE/+) mice. This finding is further supported by increased total deoxypyridinoline in serum.

CONCLUSIONS

Our results imply that TNF(DeltaARE/+) mice have a disturbed Ca(2+) homeostasis characterized by reduced duodenal and renal Ca(2+) transporters, diminished 1,25(OH)(2)D(3) levels, and increased bone resorption associated with profound bone abnormalities.

The paradoxical effects of vitamin D on type 1 mediated immunity

Low vitamin D status is associated with an increased risk of Th1 mediated autoimmune diseases like inflammatory bowel disease. 1,25(OH)(2)D(3) treatments have been shown to suppress Th1 mediated immunity and protect animals from experimental autoimmunity. Th1 mediated immunity is important for clearance of a number of different infectious diseases. For tuberculosis 1,25(OH)(2)D(3) treatment is associated with decreased Th1 mediated immunity but increased bactericidal activity. Systemic candidiasis is unaffected by 1,25(OH)(2)D(3) treatment. The seemingly paradoxical effects of 1,25(OH)(2)D(3) and vitamin D on Th1 mediated autoimmunity versus infectious immunity point to a broad array of vitamin D targets in the immune system. The interplay of these vitamin D targets and their impact on the host-immune response then dictate the outcome.

A review of complementary and alternative approaches to immunomodulation

Current Western therapies for inflammatory diseases are suboptimal; increasingly, patients are turning to complementary and alternative medicine for symptom relief and improved quality of life. There is emerging evidence that many of these therapies have the ability to modulate the immune system and disrupt the proinflammatory cascade through a variety of mechanisms, including antioxidant effects, alterations in cell signaling (in particular the nuclear factor (NF)-kappaB pathway), cytokines, proinflammatory mediators, and disruption of bacterial flora. Using inflammatory bowel disease (IBD) as a model of inflammation, we explore the principal complementary and alternative medicine treatments that show promise in this regard, namely, resveratrol, green tea, curcumin, boswellia, fish oil, vitamin D, and probiotics. With each agent, we detail the mechanisms that have been described with regard to immune modulation, discuss the medical conditions for which it has been evaluated, and explore the data to date for the prevention or treatment of IBD.

Integrative medicine in gastrointestinal disease: evaluating the evidence

Current Western therapies for many gastrointestinal diseases are suboptimal and potentially toxic. The majority of patients with digestive diseases are turning to complementary and alternative medicine for symptom relief and improved quality of life, due to dissatisfaction with conventional medical therapies. There is emerging evidence that many of these complementary and alternative medicine modalities are highly effective in modulating the immune system, disrupting the proinflammatory cascade and restoring digestive health while improving patients' quality of life. We present evidence to support the potential utility of complementary and alternative medicine modalities for irritable bowel syndrome and inflammatory bowel disease. For each condition, we detail the proposed mechanisms of action and explore the current data for the prevention and/or treatment of disease.

Nutritional considerations in heart failure

There are a number of factors related to heart failure pathophysiology and treatment that influence nutrient requirements for patients. These include catabolism, inflammation, oxidative stress, diuretic use, and presence of comorbidities. On the other hand, there is evidence that specific nutrients can alter heart failure pathophysiology. This article reviews the current evidence for nutritional recommendations regarding sodium and fluid restriction, macro- and micronutrient intake, and dietary changes required by the presence of common comorbidities.

Vitamin D status in gastrointestinal and liver disease

PURPOSE OF REVIEW

The purpose of this review is to report on the vitamin D status and its relationship with bone health in individuals with gastrointestinal and liver disorders. In addition, recommendations regarding replacement and maintenance of optimal vitamin D stores, as well as the state of knowledge regarding its effect on the disease through its actions on the immune system, will be reviewed.

RECENT FINDINGS

The scientific community has revised upward the serum levels of vitamin D considered optimal, and doses of vitamin D much larger than those currently recommended may be needed to maintain these levels, especially in individuals with gastrointestinal and liver disorders. The relationship between vitamin D and bone health in this population is controversial. The role of vitamin D in the regulation of the immune system continues to be elucidated.

SUMMARY

Hypovitaminosis D is prevalent among individuals with gastrointestinal and liver disease. Although replacement and supplementation guidelines have not been well defined, practitioners should aim for a serum 25-hydroxyvitamin D level of at least 32 ng/ml. The contribution of vitamin D to the bone health of these individuals and its role in altering disease course through its actions on the immune system remain to be elucidated.

Dietary microparticles and their impact on tolerance and immune responsiveness of the gastrointestinal tract

Dietary microparticles are non-biological bacterial-sized particles of the gastrointestinal lumen that occur due to endogenous formation (calcium phosphate) or following oral exposure (exogenous microparticle). In the UK, about 40 mg (10(12)) of exogenous microparticles are ingested per person per day, through exposure to food additives, pharmaceutical/supplement excipients or toothpaste constituents. Once ingested, exogenous microparticles are unlikely to pass through the gastrointestinal tract without adsorbing to their surfaces some ions and molecules of the intestinal lumen. Both entropy and ionic attraction drive such interactions. Calcium ions are especially well adsorbed by dietary microparticles which then provide a positively charged surface for the attraction (adsorption) of other organic molecules such as lipopolysaccharides, peptidoglycans or protein antigen from the diet or commensal flora. The major (but not only) sites of microparticle entry into intestinal tissue are the M-cell rich lymphoid aggregates (termed Peyer's patches in the small bowel). Indeed, it is well established that this is an efficient transport route for non-biological microparticles although it is unclear why. We hypothesise that this pathway exists for "endogenous microparticles" of calcium phosphate, with immunological and physiological benefit, and that "exogenous dietary microparticles", such as titanium dioxide and the silicates, hijack this route. This overview focuses on what is known of these microparticles and outlines their potential role in immune tolerance of the gut (endogenous microparticles) or immune activation (exogenous microparticles) and inflammation of the gut.

Calcitriol analog ZK191784 ameliorates acute and chronic dextran sodium sulfate-induced colitis by modulation of intestinal dendritic cell numbers and phenotype

AIM: To investigate the effects of ZK1916784, a low calcemic analog of calcitriol on intestinal inflammation.

METHODS: Acute and chronic colitis was induced by dextran sodium sulfate (DSS) according to standard procedures. Mice were treated intraperitoneally with ZK1916784 or placebo and colonic inflammation was evaluated. Cytokine production by mesenterial lymph node (MLN) cells was measured by ELISA. Immunohistochemistry was performed to detect intestinal dendritic cells (DCs) within the colonic tissue, and the effect of the calcitriol analog on DCs was investigated.

RESULTS: Treatment with ZK191784 resulted in significant amelioration of disease with a reduced histological score in acute and chronic intestinal inflammation. In animals with acute DSS colitis, down-regulation of colonic inflammation was associated with a dramatic reduction in the secretion of the proinflammatory cytokine interferon (IFN)-γ and a significant increase in intereleukin (IL)-10 by MLN cells. Similarly, in chronic colitis, IL-10 expression in colonic tissue increased 1.4-fold when mice were treated with ZK191784, whereas expression of the Th1-specific transcription factor T-beta decreased by 81.6%. Lower numbers of infiltrating activated CD11c⁺ DCs were found in the colon in ZK191784-treated mice with acute DSS colitis, and secretion of proinflammatory cytokines by primary mucosal DCs was inhibited in the presence of the calcitriol analog.

CONCLUSION: The calcitriol analog ZK191784 demonstrated significant anti-inflammatory properties in experimental colitis that were at least partially mediated by the immunosuppressive effects of the derivate on mucosal DCs.

Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction?

Vitamin D insufficiency is common in the United States; the elderly and African-Americans are at particularly high risk of deficiency. This review, written for a broad scientific readership, presents a critical overview of scientific evidence relevant to a possible causal relationship between vitamin D deficiency and adverse cognitive or behavioral effects. Topics discussed are 1) biological functions of vitamin D relevant to cognition and behavior; 2) studies in humans and rodents that directly examine effects of vitamin D inadequacy on cognition or behavior; and 3) immunomodulatory activity of vitamin D relative to the proinflammatory cytokine theory of cognitive/behavioral dysfunction. We conclude there is ample biological evidence to suggest an important role for vitamin D in brain development and function. However, direct effects of vitamin D inadequacy on cognition/behavior in human or rodent systems appear to be subtle, and in our opinion, the current experimental evidence base does not yet fully satisfy causal criteria. Possible explanations for the apparent inconsistency between results of biological and cognitive/behavioral experiments, as well as suggested areas for further research are discussed. Despite residual uncertainty, recommendations for vitamin D supplementation of at-risk groups, including nursing infants, the elderly, and African-Americans appear warranted to ensure adequacy.

Low dietary calcium levels modulate mucosal caspase expression and increase disease activity in mice with dextran sulfate sodium induced colitis

Dietary calcium (Ca) positively modulates the susceptibility to colon cancer, but its effects on related or earlier colonic pathologies, such as inflammation and mucosal dysregulation, are poorly understood. We tested the effects of differing dietary Ca levels on acute dextran sulfate sodium (DSS)-induced colitis in mice. BALB/c mice received a normal Ca (NCa) diet (0.5% Ca), a high Ca (HCa) diet (1.5% Ca), a low Ca (LCa) diet (0.05% Ca), or a very low Ca (VLCa) diet (0.009% Ca) for 3 wk. Mucosal caspases 1, 3, and 9 were assessed by Western blotting, and the histological crypt score was assessed by microscopy. Half of the mice in each group received DSS (1.5%) for 20 d in their drinking water, and disease activity was assessed. Increasing or lowering dietary Ca increased mucosal caspases (P < 0.0001 vs. NCa). Crypt scores increased with decreasing dietary Ca levels (P < 0.0001, r = -0.675), indicating that elevated caspases in LCa groups reflected early subclinical inflammation. DSS-induced disease activity was higher in mice fed low dietary Ca levels [P < 0.0001, VLCa and DSS vs. NCa and DSS (NCaDSS) and P < 0.005, LCa and DSS vs. NCaDSS], and mice from the VLCa group were moribund within 11 d of DSS administration. Those in the HCa group did not differ greatly from controls. Together, these data indicate that Ca protects against DSS-induced colitis in mice. The mechanisms are unclear, but the calcium-sensing receptor and/or luminal precipitates of calcium phosphate microparticles may be involved. Whether these observations can be extended to patients with colitis or infectious diarrhea deserves consideration.

1,25-dihydroxyvitamin D3 and dexamethasone increase interleukin-10 production in CD4+ T cells from patients with Crohn's disease

BACKGROUND AND AIM

In Crohn's disease (CD), epidemiological data and animal studies suggest that vitamin D (vitD) has protective immune-modulating properties. 1,25-dihydroxyvitamin D3 and dexamethasone (DEX) induce interleukin (IL)-10 productions in healthy controls (HC) T cells. We studied if 1,25-dihydroxyvitamin D3 with and without DEX could induce IL-10 production, downregulate pro-inflammatory Interferon (IFN)-gamma and Tumor Necrosis Factor (TNF)-alpha production, and influence cell kinetics in peripheral CD4+ T cells from CD patients.

METHODS

CD4+ T cells were separated from peripheral blood from CD patients and HC. Cells were activated by anti-CD3 and anti-CD28 in the presence of 1,25-dihydroxyvitamin D3 and/or DEX. Cytokine levels, proliferation, and apoptosis were measured following 7 days of culture.

RESULTS

In T cells from CD patients, 1,25-dihydroxyvitamin D3 and DEX increased IL-10 production from a median of 0.08 ng/ml to 0.2 ng/ml (p<0.01) and downregulated IFN-gamma production from 8.3 ng/ml to 3.1 ng/ml (p<0.01). The induced IL-10 increase in cultures from HC (0.2 ng/ml to 1.0 ng/ml, p<0.01) was significantly higher than in CD patients (p<0.05). In CD cultures, the IL-4 production increased from 0.3 ng/ml to 0.5 ng/ml (p<0.01) and IL-6 production from 2.5 ng/ml to 6.1 ng/ml (p<0.05). Similar changes in cytokine levels were observed with 1,25-dihydroxyvitamin D3 independently of DEX. In addition, 1,25-dihydroxyvitamin D3 and DEX decreased proliferation and reduced viability of T cells.

CONCLUSION

We found that 1,25-dihydroxyvitamin D3 with and without DEX stimulation increased IL-10 and reduced IFN-gamma production. These findings suggest that vitD may play a therapeutic role in CD.

Effect of 1,25-dihydroxy-vitamin D3 in experimental sepsis

BACKGROUND

In addition to the regulation of calcium homeostasis, vitamin D affects the cellular immune system, targets the TNF-alpha pathway and increases vasoconstrictor response to angiotensin II. We therefore examined the effect of 1,25-dihydroxy-vitamin D(3) on coagulation and organ failure in experimental sepsis in the rat.

METHODS

Three series of placebo-controlled studies were conducted. All rats were pre-treated with daily SC injections of 1,25-dihydroxy-vitamin D(3) 100 ng/kg or placebo vehicle for 3 days. In study 1, sepsis was accomplished by abdominal surgery comprising a coecal ligation and puncture with a 1,2 mm needle, or sham surgery. In study 2, the rats had a single IP injection of lipopolysaccharide from E. Coli 0111:B4 (LPS) 8 mg/kg, or placebo. In study 3, an hour-long IV infusion of LPS 7 mg/kg, or placebo was given.

RESULTS

All three models of sepsis showed significant effects on coagulation and liver function with reduced thrombocyte count and prothrombin time together with elevated ALT and bilirubin (p<0.05) as compared to controls. In study 1, the vitamin D treated rats maintained normal platelet count, whereas the vehicle treated rats showed a significant reduction (p<0.05). This effect of vitamin D on platelets was not found in the LPS-treated groups. We found no significant differences between vitamin D and placebo-treated rats with regards to liver function.

CONCLUSION

The present data suggest a positive modulating effect of 1,25-dihydroxy-vitamin D(3) supplementation on sepsis-induced coagulation disturbances in the coecal ligation and puncture model. No such effect was found in LPS-induced sepsis.

1,25-Dihydroxyvitamin D3 induces biphasic NF-κB responses during HL-60 leukemia cells differentiation through protein induction and PI3K/Akt-dependent phosphorylation/degradation of IκB

1,25-dihydroxyvitamin D(3) (VD(3)) induces differentiation in a number of leukemia cell lines and under various conditions is able to either stimulate or inhibit nuclear factor kappa B (NF-kappaB) activity. Here we report a time-dependent biphasic regulation of NF-kappaB in VD(3)-treated HL-60 leukemia cells. After VD(3) treatment there was an early approximately 4 h suppression and a late 8-72 h prolonged reactivation of NF-kappaB. The reactivation of NF-kappaB was concomitant with increased IKK activities, IKK-mediated IkappaBalpha phosphorylation, p65 phosphorylation at residues S276 and S536, p65 nuclear translocation and p65 recruitment to the NF-kappaB/vitamin D responsive element promoters. In parallel with NF-kappaB stimulation, there was an up-regulation of NF-kappaB controlled inflammatory and anti-apoptotic genes such as TNFalpha, IL-1beta and Bcl-xL. VD(3)-triggered reactivation of NF-kappaB was associated with PI3K/Akt phosphorylation. PI3K/Akt antagonists suppressed VD(3)-stimulated IkappaBalpha phosphorylation as well as NF-kappaB-controlled gene expression. The early approximately 4 h VD(3)-mediated NF-kappaB suppression coincided with a prolonged increase of IkappaBalpha protein which require de novo protein synthesis, lasted for as least 72 h and was insensitive to MAPK, IKK or PI3K/Akt inhibitors. Our data suggest a novel biphasic regulation of NF-kappaB in VD(3)-treated leukemia cells and our results may have provided the first molecular explanation for the contradictory observations reported on VD(3)-mediated immune-regulation.

Induction of cathelicidin in normal and CF bronchial epithelial cells by 1,25-dihydroxyvitamin D(3)

BACKGROUND

Antimicrobial peptides (AMPs) such as cathelicidins contribute to initial defense of the airway against inhaled pathogens. Recent studies have shown that the hormonally active form of vitamin D(3), 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) up-regulates AMP gene expression in several established cell lines. Furthermore, serum levels of vitamin D are often deficient in cystic fibrosis (CF) patients.

METHODS

We investigated the effect of 1,25(OH)(2)D(3) on AMP mRNA levels in primary cultures of normal human bronchial epithelial (NHBE) cells by real-time PCR, and protein levels by Western blot. Antimicrobial activity of airway surface fluid from these cells was measured by in vitro assay against laboratory strains of bacteria.

RESULTS

Treatment of NHBE cells with 1,25(OH)(2)D(3) (10(-8)M), resulted in a 10-fold up-regulation of cathelicidin mRNA levels after 12 h, which was augmented 2-fold with co-incubation of 1 mM Calcium. Moreover, 1,25(OH)(2)D(3) induced antimicrobial activity against the airway pathogens Bordetella bronchiseptica and Pseudomonas aeruginosa. 1,25(OH)(2)D(3) induced cathelicidin mRNA expression equally in both normal and CF bronchial epithelial cells.

CONCLUSIONS

Elucidation of the effect of 1,25(OH)(2)D(3) on cathelicidin expression in NHBE cells and CF bronchial epithelial cells will aid in the development of novel therapeutic agents for treatment of airway infections in CF.