Browsing by Subject "Vitamin D"

Now showing 1 - 7 of 7

Cellular stress regulates fibroblast growth factor 23 (FGF23) und αklotho
(2023) Münz, Sina; Föller, Michael
Cellular stress is defined as the impairment of regular cell function by internal or external stimuli including critical temperatures, energy deficiency, infections, mechanic injury, or chemical noxae. The present thesis aims to investigate the influence of cellular stress on the expression of FGF23 and αklotho. FGF23 is predominantly produced in bone and regulates the phosphate excretion in the kidney. Thereby, αklotho functions as a co-receptor for FGF23. By binding to the FGF receptor-αklotho complex, FGF23 reduces the reabsorption of phosphate from the tubular lumen by decreasing the abundance of sodium-phosphate co-transporters. Furthermore, FGF23 decreases the synthesis of 1,25(OH)2D3, active vitamin D, and increases its degradation. 1,25(OH)2D3 is a regulator of intestinal phosphate absorption and therefore, FGF23 additionally reduces dietary phosphate uptake. Chronically elevated FGF23 is associated with numerous disorders such as kidney disease or CVD. Beside its function as a co-receptor of FGFR, αklotho has many beneficial FGF23-independent functions. It has originally been identified as an anti-aging hormone, as a loss-of-function mutation in the αklotho gene causes numerous aging-like symptoms such as vascular and tissue calcification, osteoporosis, sterility, and an early death. The present papers investigated the influence of cytostatic drugs cisplatin, paclitaxel, and doxorubicin as well as apoptosis inducers PAC-1 and serum depletion on the regulation of FGF23 and αklotho. In UMR106 rat osteoblast-like osteosarcoma cells, a 24 or 48 h-treatment with cisplatin, doxorubicin, PAC-1, or serum reduction and depletion significantly up-regulated Fgf23 expression. Under serum depletion, also FGF23 protein secretion was increased. In addition to FGF23, cisplatin and doxorubicin also increased gene expression of pro-inflammatory cytokine Il6 hinting at the presence of necrotic cell death. By inhibiting Il-6 membrane receptor gp130 it has been shown, that FGF23 stimulation partially depended on IL-6 signaling. The stimulation of FGF23 by inflammatory mediators including IL-6, TNFα, TGF-β, or IL-1β has already been reported by others. Furthermore, inflammatory diseases such as rheumatoid arthritis, CKD, or inflammatory bowel disease are associated with excess FGF23 serum concentrations. In this regard, we investigated gene expression and activation of the transcription factor NFκB, which regulates numerous inflammatory functions. Cisplatin and doxorubicin increased the expression of NFκB subunit Rela and cisplatin also stimulated the phosphorylation of NFκB. Independently, NFκB inhibitors wogonin and withaferin A attenuated cisplatin-mediated stimulation of FGF23 indicating, that FGF23 excess was in part promoted by NFκB signaling. These investigations confirmed a strong impact of cisplatin or doxorubicin-induced inflammation on FGF23 synthesis, whereas PAC-1 and serum depletion have reported to directly induce apoptosis, which is commonly not associated with inflammation. Known factors, induced by all cytotoxic substances used here, are the formation of ROS and activation of HIF1α. Both are positive regulators of FGF23, leading to the conclusion, that cellular stress might regulate FGF23 via HIF1α or oxidative stress. FGF23 excess results in increased bone resorption and suppressed bone formation. Likewise, also chemotherapeutic drugs and serum deficiency reduce bone density. Therefore, the stimulation of FGF23 may cause or further stimulate bone resorption. In paper 2, the influence of the cytostatic drugs cisplatin, paclitaxel, and doxorubicin as well as apoptosis inductors PAC-1 or serum depletion on αklotho expression in renal MDCK, NRK-52E, and HK-2 cells has been investigated. In fact, all cytotoxic compounds stimulated gene expression of αklotho while decreasing cell proliferation and viability. By using a combined apoptosis and necrosis assay, we confirmed the induction of apoptosis but also necrosis to a variable extent. Additionally, the transcriptional regulation of apoptotic proteins of the BCL-2 family was assessed and confirmed apoptosis stimulation. Transcription factor PPARγ is a known positive regulator of αklotho. In MDCK cells, we detected a significant influence of cisplatin-mediated stimulation of PPARγ mRNA on the αklotho increase. Furthermore, cisplatin, doxorubicin, PAC-1, and serum deprivation also up-regulated FGFR production in MDCK cells. In cancer cells, overexpression of FGFR is associated with enhanced resistance against chemotherapeutic drugs. Consequently, αklotho and FGFR1 stimulation may be a protective mechanism to prevent hyperphosphatemia during diseases. However, human HK-2 cells treated with cisplatin, paclitaxel, doxorubicin, or serum depletion significantly down-regulated αklotho expression and protein secretion. PAC-1 did not change the expression or production of αklotho in HK-2 cells, which might be explained by the minor effect of PAC-1 on non-carcinogenic cells lacking an overexpression of procaspase-3. The differential regulation of αklotho in MDCK and NRK-52E versus HK-2 cells by cytotoxic stress might have numerous causes. For instance, there is evidence of an increased sensitivity of HK-2 cells to stress stimuli but a better comparability to the animal model. However, immortalized cell lines can not completely reflect the conditions of native tissue especially with regard to cell death. Furthermore, the species, sex or age of the donor organism as well as passage number of the cells and drug transporter expression might impact αklotho regulation. Additionally, the mode of cell death determined by intracellular ATP homeostasis and its regulation of AMPK might play an important role in αklotho regulation. However, all these theories need to be further addressed. In summary, inflammation, ROS formation, or the activation of HIF1α are all reported to correlate in a negative manner with αklotho production or serum levels. αklotho down-regulation may be a tool to increase cell proliferation or prevent hypophosphatemia. In contrast, AMPK activation by intracellular ATP restriction may positively regulate αklotho to promote cell protection and avoid hyperphosphatemia.
Nutrition and tuberculosis in Ethiopia : the role of vitamin D2 derived from sun exposed oyster mushroom on the treatment outcomes of tuberculosis
(2019) Keflie, Tibebeselassie Seyoum; Biesalski, Hans-Konrad
Tuberculosis (TB) is an old infectious disease which causes ill-health among millions of people each year. Effective anti-TB drugs are available since 1950’s, but still the global burden of TB remains enormous. The disease is very complex and there is a need to look for supportive treatment to the standard anti-TB drugs. Cognizant of this, the present doctoral study was undertaken by giving emphasis on nutrition and TB in Ethiopia. The aim of this doctoral dissertation thesis was to deal with the nutritional situation of people with and without TB and come-up with solutions that could support the effort of combating TB. In this thesis, five papers (four published and one submitted) were included. The first paper encompassed the study of dietary and nutritional assessment. In this study, dietary inadequacy, poor nutritional quality and high risk of micro nutrient deficiencies were identified. The main dietary pattern included cereals, vegetables and legumes. About one-third of the population consumed animal source food (ASF). Malnutrition was the common problem in people with and without TB. This suggested that malnutrition may pave the way for TB. The case-control study in the second paper revealed that more than one-half of TB patients had vitamin A and zinc deficiencies. More than three-fourth of TB patients had below half of the energy fulfillment. The protein intake was above the average fulfillment, but most TB patients relied on cereal-based diets. Patients with TB used a larger proportion of proteins from oral feeding for oxidation and hence for energy production. About half of the patients were undernourished. Thus, vitamin A and zinc deficiencies along with protein-energy malnutrition need to be addressed in the management program of TB. The third paper included systematic review which explored the existence of vitamin D deficiency (VDD). Sunshine, which is very important for the synthesis of vitamin D under the skin is widely available in Africa throughout the year. Surprisingly, more than three-fourth of TB patients in Africa had VDD and vitamin D insufficiency (VDI). Statistically significant variables such as use of sun protection (lack of sun-exposure), inadequate dietary intake, low body mass index (BMI), high skin pigmentation, use of drugs (anti-retro viral and /or anti-TB), low socioeconomic status, rainy season, covering body skin with clothes, old age and co-morbidity were identified as the main predictor variables that hampered the status of vitamin D. Vitamin D can be obtained from dietary intakes apart from endogenous synthesis after sun exposure. Mushroom as such, is a potential non-animal source of vitamin D. The experimental study in the fourth paper revealed that sun-exposure significantly increased the content of vitamin D2 in oyster mushroom. Increasing the surface area for sun-exposure enhanced the production of vitamin D2. Other factors such as duration of sun-exposure and moisture content determined the production of vitamin D2. Exposing slices of oyster mushroom to direct sun for brief period provided enough vitamin D2 that could satisfy the current recommended dietary allowance (RDA) of vitamin D without any visible changes in color and texture. The study in the fifth paper was a randomized controlled trial and demonstrated for the first time the role of mushroom-derived vitamin D2 on the treatment outcomes of TB. Intervention with vitamin D2 derived from sun-exposed oyster mushrooms brought significant improvement in vitamin D status, clinical outcomes and immunological responses, but not in sputum smear and culture conversion. The intervention corrected VDD in more than one-third of TB patients. About one-third of the variability in TB score in the intervention group was accounted for by the change in the serum 25 hydroxy (OH) vitamin D level. There were also significant improvements in the serum IFN-gamma and cathelicidin LL-37 peptide levels after intervention. The balance of cytokines was skewed to TH1 responses due to high level of IFN-gamma. Thus, mushroom-derived vitamin D2 could serve as potential, safe, easily available and cost-effective adjunctive therapy for TB. Taken collectively, foods enriched with vitamin D need to be included in the national TB control program to support the first line anti-TB drugs, increase the cure rate and reduce the infectiousness of TB.
Nutritional status and its impact on outcome in patients undergoing allogeneic haematopoietic cell transplantation and an experimental trial to improve the supply of a specific micronutrient
(2012) Urbain, Paul; Biesalski, Hans-Konrad
The first two studies investigated the course of the nutritional status in patients un-dergoing allogeneic haematopoietic cell transplantation (alloHCT) and the validity of nutritional markers as independent risk factors for outcome. In line with others, we detected an overall good nutritional status before alloHCT by employing quick screening tools such as BMI and the SGA questionnaire for identifying malnutrition. However, upon closer inspection, we observed unintentional weight loss previous to alloHCT to be a frequent condition, detecting many more underweight patients using age- and gender-specific BMI classification and overall low bioelectrical impedance phase angle values at admission. Deterioration in nutritional status during the early post-transplant period was significant in the cohort. Furthermore, we identified ano-rexic patients and those with clinically-relevant aGVHD (≥°II) to have an increased risk for a decline in nutritional status during early rehabilitation. In addition, it could be demonstrated for the first time that the pretransplant phase angle (≤25th percen-tile) used as a standardised value was an independent predictor for 2-year overall survival, non-relapse mortality and progression-free survival. BMI adjusted for age and gender emerged as an independent risk factor for OS and NRM. Both of these nutritional markers performed better than numerous generally-accepted risk factors, and they were the only significant prognostic values for outcome in this cohort be-sides HLA-C compatibility, donor and remission status. In addition, these two nutri-tional markers are theoretically modifiable during the often lengthy treatment period before transplantation. Further investigation is necessary to demonstrate whether or not the phase angle can be increased by strategies that enhance muscle mass via physical training together with nutritional support, and whether it can prevent dete-rioration in nutritional status and lead to beneficial effects on outcome after alloHCT. The third study investigated the association between AOX status (α-tocopherol, ascorbic acid and ß-carotene) in buccal mucosa cells (BMC) or plasma and the risk of developing oral mucositis (OM) after conditioning chemotherapy. We observed no significant differences in baseline AOX concentrations in plasma or BMC among the different OM groups (no or mild, ulcerative and severe OM), revealing that no single AOX has predictive value for the incidence or severity of OM after conditioning chemotherapy. However, patients with an overall good plasma AOX status tended to require a shorter duration of parenteral nutrition, which is a relevant clinical and economic marker for OM treatment compared to patients with at least one plasma AOX beneath the normal range. These findings may indicate that an intact antioxidative network is more relevant than any one AOX for lowering the OM risk. Future studies should consider both the exogenous- and endogenous AOX systems. The fourth study revealed a generally low serum 25-hydroxyvitamin D [25(OH)D3] status in these patients at admission. Furthermore, their 25(OH)D3 status remained low during the early post-transplant period, showing a trend towards further deterio-ration, especially in patients with corticosteroid-treated aGVHD. In addition, we con-ducted a detailed investigation of the impact of well-known influencing factors on baseline serum 25(OH)D3 status, revealing only higher body fat mass to be an inde-pendent risk factor for reduced baseline status. In fact the most important influenc-ing factors, namely dietary factors and season, revealed no detectable impact, most probably due to inadequate oral intake, prolonged disease history, and hospitalisa-tion. In conclusion, these results provide a clear rationale for the use at least of vitamin D-containing multivitamin preparations in standard multivitamin prescrip-tions, and for the monitoring of vitamin D status at regular intervals from the date of diagnosis. The fifth study was a randomised controlled trial revealing for the first time in humans that the bioavailability of vitamin D2 from vitamin D2-enhanced button mushrooms via UV-B irradiation is effective in improving vitamin D status in young, healthy adults and not different than a vitamin D2 supplement. The vitamin D2 enhancement of mushrooms boosts their nutraceutical value by creating both an abundant and excellent source of vitamin D2 that opens up new opportunities in fighting widespread vitamin D deficiency.
Previtamin D2, vitamin D2, and vitamin D4 amounts in different mushroom species irradiated with ultraviolet (UV) light and occurrence of structurally related photoproducts
(2024) Sommer, Katrin; Hillinger, Marissa; Vetter, Walter
Mushrooms are rich in ergosterol and ergosta‐5,7‐dienol, which can be partly converted into vitamin D2 and D4 through ultraviolet (UV) light exposure. Typically, mushrooms have very low vitamin D contents, but it can be increased by UV irradiation. This process generates additional photoisomers scarcely studied in mushrooms due to analytical challenges. Here, we developed a new solid phase extraction (SPE) method to separate vitamin D2, vitamin D4, and other tri‐ and pentacyclic photoisomers from the much higher abundant ergosterol. Subsequent GC/MS analysis enabled the detection of ten photoisomers in eight UV‐treated mushroom species, including vitamin D2 (previtamin D2, tachysterol2, two suprasterol2 and trans‐vitamin D2 isomers) and vitamin D4 (previtamin D4). Quantitated vitamin D2 contents of 10–540 µg/100 g dry weight agreed well with the sparse literature data available for the investigated mushroom species. In addition, previtamin D2 (nd–1950 µg/100 g dry weight) and vitamin D4 (10–140 µg/100 g dw) were quantified in the samples. The content and photoproduct compositions varied considerably between different mushroom species. Practical applications: The novel SPE method can be applied to study the vitamin D and photoisomer content of mushrooms.
Prostaglandin E2 signaling through prostaglandin E receptor subtype 2 and Nurr1 induces fibroblast growth factor 23 production
(2024) Feger, Martina; Hammerschmidt, Katharina; Liesche, lona; Rausch, Steffen; Alber, Jana; Föller, Michael
Bone cells produce fibroblast growth factor 23 (FGF23), a hormone regulating renal phosphate and vitamin D homeostasis, and a paracrine factor produced in further tissues. Chronic kidney disease and cardiovascular disorders are associated with early elevations of plasma FGF23 levels associated with clinical outcomes. FGF23 production is dependent on many conditions including inflammation. Prostaglandin E2 (PGE2) is a major eicosanoid with a broad role in pain, inflammation, and fever. Moreover, it regulates renal blood flow, renin secretion, natriuresis as well as bone formation through prostaglandin E receptor 2 (EP2). Here, we studied the role of PGE2 and its signaling for the production of FGF23. Osteoblast-like UMR-106 cells were exposed to EP receptor agonists, antagonists or RNAi. Wild type and EP2 knockout mice were treated with stable EP2 agonist misoprostol. Fgf23 or Nurr1 gene expression was determined by quantitative real-time PCR, hormone and further blood parameters by enzyme-linked immunosorbent assay and colorimetric methods. PGE2 and EP2 agonists misoprostol and butaprost enhanced FGF23 production in UMR-106 cells, effects mediated by EP2 and transcription factor Nurr1. A single dose of misoprostol up-regulated bone Fgf23 expression and FGF23 serum levels in wild type mice with subtle effects on parameters of mineral metabolism only. Compared to wild type mice, the FGF23 effect of misoprostol was significantly lower in EP2-deficient mice. To conclude, PGE2 signaling through EP2 and Nurr1 induces FGF23 production. Given the broad physiological and pathophysiological implications of PGE2 signaling, this effect is likely of clinical relevance.
Short‐term fasting of mice elevates circulating fibroblast growth factor 23 (FGF23)
(2023) Feger, Martina; Alber, Jana; Strotmann, Jörg; Grund, Andrea; Leifheit‐Nestler, Maren; Haffner, Dieter; Föller, Michael
Aims: Phosphate and vitamin D homeostasis are controlled by fibroblast growth factor 23 (FGF23) from bone suppressing renal phosphate transport and enhancing 24-hydroxylase (Cyp24a1), thereby inactivating 1,25(OH)2D3. Serum FGF23 is correlated with outcomes in several diseases. Fasting stimulates the production of ketone bodies. We hypothesized that fasting can induce FGF23 synthesis through the production of ketone bodies. Methods: UMR106 cells and isolated neonatal rat ventricular myocytes (NRVM) were treated with ketone body β-hydroxybutyrate. Mice were fasted overnight, fed ad libitum, or treated with β-hydroxybutyrate. Proteins and further blood parameters were determined by enzyme-linked immunoassay (ELISA), western blotting, immunohistochemistry, fluorometric or colorimetric methods, and gene expression by quantitative real-time polymerase chain reaction (qRT-PCR). Results: β-Hydroxybutyrate stimulated FGF23 production in UMR106 cells in a nuclear factor kappa-light-chain enhancer of activated B-cells (NFκB)-dependent manner, and in NRVMs. Compared to fed animals, fasted mice exhibited higher β-hydroxybutyrate and FGF23 serum levels (based on assays either detecting C-terminal or intact, biologically active FGF23 only), cardiac, pancreatic, and thymic Fgf23 and renal Cyp24a1 expression, and lower 1,25(OH)2D3 serum concentration as well as renal Slc34a1 and αKlotho (Kl) expression. In contrast, Fgf23 expression in bone and serum phosphate, calcium, plasma parathyroid hormone (PTH) concentration, and renal Cyp27b1 expression were not significantly affected by fasting. Conclusion: Short-term fasting increased FGF23 production, as did administration of β-hydroxybutyrate, effects possibly of clinical relevance in view of the increasing use of FGF23 as a surrogate parameter in clinical monitoring of diseases. The fasting state of patients might therefore affect FGF23 tests.
Vitamin A- and D-deficient diets disrupt intestinal antimicrobial peptide defense involving Wnt and STAT5 signaling pathways in mice
(2023) Filipe Rosa, Louisa; Petersen, Patricia P.; Görtz, Lisa F.; Stolzer, Iris; Kaden-Volynets, Valentina; Günther, Claudia; Bischoff, Stephan C.
Vitamin A and D deficiencies are associated with immune modulatory effects and intestinal barrier impairment. However, the underlying mechanisms remain unclear. C57BL/6J mice were fed either a diet lacking in vitamin A (VAd), vitamin D (VDd) or a control diet (CD) for 12 weeks. Gut barrier function, antimicrobial peptide (AMP) defense and regulatory pathways were assessed. VAd mice compared to CD mice showed a reduced villus length in the ileum (p < 0.01) and decreased crypt depth in the colon (p < 0.05). In both VAd- and VDd-fed mice, ileal α-defensin 5 (p < 0.05/p < 0.0001 for VAd/VDd) and lysozyme protein levels (p < 0.001/p < 0.0001) were decreased. Moreover, mRNA expression of lysozyme (p < 0.05/p < 0.05) and total cryptdins (p < 0.001/p < 0.01) were reduced compared to controls. Furthermore, matrix metalloproteinase-7 (Mmp7) mRNA (p < 0.0001/p < 0.001) as well as components of the Wnt signaling pathway were decreased. VAd- and VDd-fed mice, compared to control mice, exhibited increased expression of pro-inflammatory markers and β-defensins in the colon. Organoid cell culture confirmed that vitamins A and D regulate AMP expression, likely through the Jak/STAT5 signaling pathway. In conclusion, our data show that vitamin A and D regulate intestinal antimicrobial peptide defense through Wnt and STAT5 signaling pathways.