Intramammary calcitriol treatment of mastitis alters profile of milk somatic cells and indicators of redox activity in milk

The objective of this experiment was to determine the effect of intramammary calcitriol treatment on indicators of inflammation during an intramammary bacterial infection. Lactating Holstein cows were challenged with intramammary Streptococcus uberis. At the onset of mild or moderate mastitis, cows were randomly assigned to receive 10 µg of intramammary calcitriol (CAL, n = 7) or placebo control (CON; n = 6) after every milking for 5 days. Data were analyzed by ANOVA with mixed models using the MIXED procedure of SAS with significance declared at P ≤ 0.05. Milk somatic cells, mastitis severity scores, rectal temperatures, and milk bacterial counts did not differ between treatments. Calcitriol decreased the percentage of CD11b+CD14- cells in milk compared with CON (CON = 81 vs. CAL = 61 ± 5%). Antioxidant potential and concentrations of 15-F2t- isoprostanes in milk of infected quarters also were lower in CAL compared with CON. Transcripts for the 25-hydroxyvitamin D 24-hydroxylase and inducible nitric oxide synthase were greater in milk somatic cells of CAL compared with CON, but those for β-defensin 7, metallothionein 1 A and 2 A, thioredoxin and thioredoxin reductase did not differ between treatments. Although clinical signs of severity did not differ, CAL influenced the composition of milk somatic cells and redox activity in milk of infected quarters.

Effect of vitamin D source and amount on vitamin D status and response to endotoxin challenge

The objectives were to test the effects of dietary vitamin D₃ [cholecalciferol (CHOL)] compared with 25-hydroxyvitamin D₃ [calcidiol (CAL)] on vitamin D status and response to an endotoxin challenge. Forty-five Holstein bull calves (5 ± 2 d of age) were blocked into weekly cohorts, fed a basal diet that provided 0.25 µg/kg body weight (BW) CHOL, and assigned randomly to 1 of 5 treatments: control [(CON) no additional vitamin D], 1.5 µg/kg BW CHOL (CHOL1.5), 3 µg/kg BW CHOL (CHOL3), 1.5 µg/kg BW CAL (CAL1.5), or 3 µg/kg BW CAL (CAL3). Calves were fed milk replacer until weaning at 56 d of age and had ad libitum access to water and starter grain throughout the experiment. Treatments were added daily to the diet of milk replacer until weaning and starter grain after weaning. Measures of growth, dry matter intake, and serum concentrations of vitamin D, Ca, Mg, and P were collected from 0 to 91 d of the experiment. At 91 d of the experiment, calves received an intravenous injection of 0.1 µg/kg BW lipopolysaccharide (LPS). Clinical and physiological responses were measured from 0 to 72 h relative to LPS injection. Data were analyzed with mixed models that included fixed effects of treatment and time, and random effect of block. Orthogonal contrasts evaluated the effects of (1) source (CAL vs. CHOL), (2) dose (1.5 vs. 3.0 µg/kg BW), (3) interaction between source and dose, and (4) supplementation (CON vs. all other treatments) of vitamin D. From 21 to 91 d of the experiment, mean BW of supplemented calves was less compared with CON calves, but the effect was predominantly a result of the CHOL calves, which tended to weigh less than the CAL calves. Supplementing vitamin D increased concentrations of 25-hydroxyvitamin D in serum compared with CON, but the increment from increasing the dose from 1.5 to 3.0 µg/kg BW was greater for CAL compared with CHOL (CON = 18.9, CHOL = 24.7 and 29.6, CAL = 35.6 and 65.7 ± 3.2 ng/mL, respectively). Feeding CAL also increased serum Ca and P compared with CHOL. An interaction between source and dose of treatment was observed for rectal temperature and derivatives of reactive metabolites after LPS challenge because calves receiving CHOL3 and CAL1.5 had lower rectal temperatures and plasma derivatives of reactive metabolites compared with calves receiving CHOL1.5 and CAL3. Supplementing vitamin D increased plasma P concentrations post-LPS challenge compared with CON, but plasma concentrations of Ca, Mg, fatty acids, glucose, β-hydroxybutyrate, haptoglobin, tumor necrosis factor-α, and antioxidant potential did not differ among treatments post-LPS challenge. Last, supplementing vitamin D increased granulocytes as a percentage of blood leukocytes post-LPS challenge compared with CON. Supplementing CAL as a source of vitamin D to dairy calves was more effective at increasing serum 25-hydroxyvitamin D, Ca, and P concentrations compared with feeding CHOL. Supplemental source and dose of vitamin D also influenced responses to the LPS challenge.

Evaluation of exosome derivatives as bio-informational reprogramming therapy for cancer

Exosomes are nanoparticle sized (100 ± 50 nm) extracellular vesicles (ECVs) that play important roles in cell-to-cell communication. They do this by utilizing their natural ability to shuttle signaling molecules across the cellular microenvironment and promote paracrine signaling. Currently, exosomes are being explored for their potential as therapeutic agents for various degenerative diseases including cancer. The rationale behind their therapeutic ability is that they can transfer signaling biomolecules, and subsequently induce metabolic and physiological changes in diseased cells and tissues. In addition, exosomes can be used as a drug delivery system and may be very effective at reducing toxicity and increasing bioavailability of therapeutic molecules and drugs. Although exosomes were first believed to be a waste product of the cell, current research has demonstrated that these particles can serve as modulators of the immune system, act as cancer biomarkers, cause re-differentiation of cancer cells, and induce apoptosis in diseased cells. Extensive research has been performed specifically using amniotic fluid-derived extracellular vesicles, named "cytosomes". While the use of cytosomes in clinical application is still in the early stages, researchers have shown great potential for these EVs in regenerative medicine as immune modulators, in controlling microbial infection and by inducing tissue repair through the activation of endogenous, tissue-specific stem cells. This review emphasizes the capabilities of specific subsets of extracellular vesicles that can potentially be used for cancer therapy, principally as a source of bi-informational reprogramming for malignant cells.

Vitamin D signaling increases nitric oxide and antioxidant defenses of bovine monocytes

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Vitamin D and interferon-gamma (IFN-γ) increased monocyte nitric oxide production

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IFN-γ decreased antioxidant potential of monocyte cultures

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Vitamin D signaling increased antioxidant potential of IFN-γ-stimulated monocytes

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Vitamin D increased abundance of metallothionein and thioredoxin transcripts

Vitamin D contributes to multiple aspects of bovine immunity and is reported to decrease the effects of mastitis and metritis in dairy cows. We hypothesized that vitamin D signaling in bovine monocytes increases antioxidant responses as part of its immunomodulatory actions. Our objectives were to assess the effects of vitamin D on oxidant and antioxidant responses of bovine monocytes. Monocytes from peripheral blood of nonpregnant, lactating Holstein cows between 90 and 300 d in milk were used for in vitro cell culture experiments. To test the effects of vitamin D on reactive oxygen metabolites (dROM) and antioxidant potential (AOP), monocytes from 14 cows were cultured in replicates for 16 h with 25-hydroxyvitamin D₃ [25(OH)D₃, 0 or 75 ng/mL] in a factorial arrangement with lipopolysaccharide (LPS, 100 ng/mL) or interferon-γ (IFN-γ, 10 ng/mL) or with no stimulation. Data were analyzed by ANOVA for main effects of 25(OH)D₃, stimulant, and interactions between 25(OH)D₃ and stimulant. Significant interactions between 25(OH)D₃ and stimulant were observed for dROM and AOP of culture supernatants. In unstimulated cultures, 25(OH)D₃ tended to increase dROM, but the opposite was observed in stimulated cultures. In contrast, LPS and IFN-γ treatments alone decreased AOP of culture supernatants, but 25(OH)D₃ counteracted the decrease in AOP caused by IFN-γ. Abundances of transcripts of genes encoding antioxidant-related proteins were measured by quantitative PCR using RNA from monocytes from 4 cows treated with 25(OH)D₃ (0 or 75 ng/mL) in a factorial arrangement with increasing concentrations of LPS (0 to 1,000 ng/mL) or IFN-γ (0 to 10 ng/mL). Treatment with 25(OH)D₃ increased transcripts of genes encoding metallothionein 1A and metallothionein 2A in the presence of IFN-γ but not LPS. Furthermore, 25(OH)D₃ increased transcripts of genes encoding thioredoxin and thioredoxin reductase, but the effect of 25(OH)D₃ did not depend on IFN-γ or LPS stimulation. In conclusion, 25(OH)D₃ increased antioxidant capacity of IFN-γ–stimulated bovine monocytes, potentially by increasing metallothionein and thioredoxin activities in monocytes.

Feeding supplemental 25-hydroxyvitamin D3 increases serum mineral concentrations and alters mammary immunity of lactating dairy cows

Objectives were to determine the effects of feeding supplemental 25-hydroxyvitamin D₃ [25(OH)D₃] on concentrations of vitamin D metabolites and minerals in serum, mammary immune status, and responses to intramammary bacterial infection in dairy cows. Sixty multiparous, pregnant lactating Holstein cows with somatic cell count <200,000/mL were blocked by days in milk and milk yield and randomly assigned to receive a daily top-dressed dietary supplement containing 1 or 3 mg of vitamin D₃ (1mgD or 3mgD), or 1 or 3 mg 25(OH)D₃ (1mg25D or 3mg25D) for 28 d (n = 15/treatment). Cows were kept in a freestall barn and fed a total mixed ration in individual feeding gates. Individual dry matter intake (DMI) and milk yield were recorded daily, and milk and blood samples were collected at 0, 7, 14, and 21 d relative to the start of treatment. At 21 d, cows fed 1mgD and 3mg25D received an intramammary challenge with Streptococcus uberis. Cows were observed for severity of mastitis, and blood and milk samples were collected every 12 h to measure inflammation. The 1mg25D and 3mg25D cows had greater serum 25(OH)D₃ concentrations at 21 d compared with 1mgD and 3mgD cows (62 ± 7, 66 ± 8, 135 ± 15, and 232 ± 26 ng/mL for 1mgD, 3mgD, 1mg25D, and 3mg25D, respectively). The 3mg25D cows had greater concentrations of Ca and P in serum at 21 d compared with other treatments (Ca = 2.38, 2.4, 2.37, and 2.48 ± 0.02 mM, 1.87, 1.88, and 2.10 ± 0.08 mM for 1mgD, 3mgD, 1mg25D, and 3mg25D, respectively). Yields of milk and milk components, DMI, body weight, and concentrations of 1,25-dihydroxyvitamin D and Mg in serum did not differ among treatments. Abundance of mRNA transcripts for interleukin-1β (IL1B) and inducible nitric oxide synthase (iNOS) in milk somatic cells before S. uberis challenge were increased in cows fed 25(OH)D₃ compared with cows fed vitamin D₃. Furthermore, IL1B, iNOS, β-defensin 7, and β-defensin 10 in milk somatic cells increased as concentrations of 25(OH)D₃ increased in serum. Cows fed 3mg25D had less severe mastitis at 60 and 72 h after challenge with S. uberis compared with cows fed 1mgD. Concentrations of bacteria, somatic cells, and serum albumin in milk after challenge did not differ between treatments; however, an interaction between treatment and day was detected for lactate dehydrogenase in milk. Expression of adhesion protein CD11b on milk neutrophils after the S. uberis challenge was greater among 3mg25D cows compared with 1mgD cows. Transcripts of CYP24A1 and iNOS in milk somatic cells during mastitis also were greater in 3mg25D cows compared with 1mgD cows. Feeding 25(OH)D₃ increased serum 25(OH)D₃ more effectively than supplemental vitamin D₃, resulting in increased serum mineral concentrations, increased expression of vitamin D-responsive genes, and altered immune responses to intramammary bacterial challenge.

Short communication: Inhibition of DNA methyltransferase and histone deacetylase increases β-defensin expression but not the effects of lipopolysaccharide or 1,25-dihydroxyvitamin D3 in bovine mammary epithelial cells

Antimicrobial peptides are a common defense against bacterial infections in many species and a significant part of the innate immune response of the bovine mammary gland. The objective of this study was to investigate the influence of epigenetic factors on vitamin D and toll-like receptor-mediated induction of β-defensins in mammary epithelial cells. Primary bovine mammary epithelial cells were treated with lipopolysaccharide (LPS, 0 or 100 ng/mL), 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃, 0 or 10 nM], and 5-aza-2'-deoxycytidine (5-Aza, inhibitor of DNA methyltransferase, 0 or 5 μM) or trichostatin A (TSA, inhibitor of histone deacetylase, 0 or 80 nM) in a factorial arrangement. Effects of treatments on β-defensin gene expression along with genes for cytokines and enzymes known to be induced by LPS or 1,25(OH)₂D₃ were evaluated by quantitative PCR. The LPS treatment induced expression of β-defensin (DEFB)3, DEFB5, DEFB7, DEFB10, enteric β-defensin (EBD), lingual antimicrobial peptide (LAP), and tracheal antimicrobial peptide (TAP); whereas, the 1,25(OH)₂D₃ treatment increased DEFB5 and DEFB7 expression and decreased LAP. The 5-Aza treatment increased expression of DEFB3, DEFB5, DEFB10, EBD, LAP, and TAP in the presence and absence of LPS. The TSA treatment increased expression of DEFB3, DEFB4, DEFB5, DEFB7, and DEFB10 in the absence of LPS but decreased LPS-induced expression of and LAP and TAP. Together these results indicate that β-defensin expression in bovine mammary epithelial cells is likely influenced by DNA methylation and histone acetylation. Investigation of environmental and nutritional factors that influence epigenetic control of β-defensins in the mammary gland may be beneficial for improving resistance to intramammary infections.

Symposium review: Targeting antimicrobial defenses of the udder through an intrinsic cellular pathway

The bovine innate immune system has a strong repertoire of antimicrobial defenses to rapidly attack infectious pathogens that evade physical barriers of the udder. Exploration of the intracrine vitamin D pathway of bovine macrophages has improved understanding of the signals that initiate antimicrobial defenses that protect the udder. In the intracrine vitamin D pathway, pathogen recognition receptors upregulate CYP27B1 mRNA that encodes for the enzyme that converts 25-hydroxyvitamin D [25(OH)D₃] to the active vitamin D hormone, 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃]. The 1,25(OH)₂D₃, in turn, is generally known to increase antimicrobial activity and decrease inflammatory responses of immune cells. In cattle specifically, 1,25(OH)₂D₃ increases nitric oxide and β-defensin antimicrobial responses of bovine monocytes. Immune activation of the intracrine vitamin D pathway, including induction of inducible nitric oxide synthase and β-defensin gene expression by 1,25(OH)₂D₃, has been documented in the mammary glands of lactating dairy cows. Furthermore, intramammary 25(OH)D₃ treatment decreased bacteria counts and indicators of mastitis severity in cows experimentally infected with Streptococcus uberis. We propose that vitamin D signaling in the udder contributes to containment of bacterial pathogens and inflammatory responses of the udder. Verification of vitamin D-mediated defenses of the mammary gland potentially provides a path for development of alternative solutions (i.e., nutritional, genetic, therapeutic) to increase mastitis resistance of dairy cows. Continued exploration of the intrinsic cellular pathways that specifically promote antimicrobial defenses of the udder, such as the vitamin D pathway, is needed to support mastitis control efforts for dairy cows.

Intramammary 1,25-dihydroxyvitamin D3 treatment increases expression of host-defense genes in mammary immune cells of lactating dairy cattle

Bacterial infection of the mammary gland activates an intracrine vitamin D pathway in macrophages of dairy cows. The active hormone of the vitamin D pathway, 1,25-dihydroxyvitamin D₃ (1,25D), stimulates nitric oxide and β-defensin responses in bovine monocyte cultures, but the effect of 1,25D on innate immune genes in the mammary gland remained unknown. Therefore, the objective of this study was to determine the effects intramammary 1,25D treatment on expression of vitamin D associated host-defenses of the bovine mammary gland. Intramammary treatment of normal, healthy mammary glands of lactating dairy cows (n=14) with 10μg 1,25D increased inducible nitric oxide synthase (iNOS) and β-defensin 7 (DEFB7) gene expression in total milk somatic cells more than two-fold relative to placebo-treated glands within 8h after treatment. The vitamin D 24-hydroxylase gene (CYP24A1) also was increased nearly 100-fold in 1,25D-treated glands within 4h after treatment but was not affected in placebo-treated glands. Both macrophages and neutrophils isolated from milk had increased CYP24A1 expression in response to 1,25D treatment but only macrophages had increased iNOS expression. Repeated intramammary 1,25D treatment, every 12h for 48h, of infected mammary glands of cows diagnosed with subclinical mastitis resulted in increased expression of CYP24A1, DEFB4, DEFB7 and iNOS genes compared to placebo-treated glands. The 1,25D treatment resulted in elevated serum 1,25D concentrations (55 vs 33pg/mL) compared to placebo but it did not change serum calcium concentrations or bacteria counts in milk of infected mammary glands. In conclusion, 1,25D upregulates iNOS and β-defensin genes in vivo in cattle and affirms earlier reports that vitamin D supports innate immune functions of cattle.

Hypothalamic leptin gene therapy reduces body weight without accelerating age-related bone loss

Excessive weight gain in adults is associated with a variety of negative health outcomes. Unfortunately, dieting, exercise, and pharmacological interventions have had limited long-term success in weight control and can result in detrimental side effects, including accelerating age-related cancellous bone loss. We investigated the efficacy of using hypothalamic leptin gene therapy as an alternative method for reducing weight in skeletally-mature (9 months old) female rats and determined the impact of leptin-induced weight loss on bone mass, density, and microarchitecture, and serum biomarkers of bone turnover (CTx and osteocalcin). Rats were implanted with cannulae in the 3rd ventricle of the hypothalamus and injected with either recombinant adeno-associated virus encoding the gene for rat leptin (rAAV-Leptin, n=7) or a control vector encoding green fluorescent protein (rAAV-GFP, n=10) and sacrificed 18 weeks later. A baseline control group (n=7) was sacrificed at vector administration. rAAV-Leptin-treated rats lost weight (-4±2%) while rAAV-GFP-treated rats gained weight (14±2%) during the study. At study termination, rAAV-Leptin-treated rats weighed 17% less than rAAV-GFP-treated rats and had lower abdominal white adipose tissue weight (-80%), serum leptin (-77%), and serum IGF1 (-34%). Cancellous bone volume fraction in distal femur metaphysis and epiphysis, and in lumbar vertebra tended to be lower (P<0.1) in rAAV-GFP-treated rats (13.5 months old) compared to baseline control rats (9 months old). Significant differences in cancellous bone or biomarkers of bone turnover were not detected between rAAV-Leptin and rAAV-GFP rats. In summary, rAAV-Leptin-treated rats maintained a lower body weight compared to baseline and rAAV-GFP-treated rats with minimal effects on bone mass, density, microarchitecture, or biochemical markers of bone turnover.

Multiple β-defensin genes are upregulated by the vitamin D pathway in cattle

Experimental models of bacterial and viral infections in cattle have suggested vitamin D has a role in innate immunity of cattle. The intracrine vitamin D pathway of bovine macrophages, however, has only been shown to activate a nitric oxide-mediated defense mechanism, as opposed to cathelicidin and β-defensin antimicrobial peptides in human macrophages. In this study we have investigated the actions of 1,25-dihydroxyvitamin D3 (1,25D) on a cluster of eleven bovine β-defensin genes on the basis of RNAseq data indicating they were targets of 1,25D in cattle. Treatment of bovine monocyte cultures with 1,25D (10 nM, 18 h) in the absence and presence of LPS stimulation increased the expression of bovine β-defensin 3 (BNBD3), BNBD4, BNBD6, BNBD7, and BNBD10 genes 5 to 10-fold compared to control (P<0.05). Treatment of lipopolysaccharide (LPS)-stimulated monocytes with 0-100 ng/mL 25-hydroxyvitamin D3 also increased BNBD3, BNBD4, BNBD7, and BNBD10 in a dose-dependent manner. Treatment of monocytes with the protein translation inhibitor, cycloheximide, however, blocked upregulation of the β-defensins in response to 1,25D suggesting the β-defensins in cattle are not direct targets of the vitamin D receptor. Furthermore, preliminary investigation of vitamin D's contribution to β-defensin expression in vivo revealed that intramammary 1,25D treatment of lactating cows increased BNBD7 expression in mammary macrophages. In conclusion, our data demonstrate that multiple β-defensin genes are upregulated by 1,25D in cattle, providing further indication that vitamin D contributes to bovine innate immunity.