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

Thioredoxin-2 suppresses hydrogen peroxide-activated nuclear factor kappa B signaling via alleviating oxidative stress in bovine adipocytes

During the periparturient period, both oxidative stress, and inflammation of adipose tissue are considered high risk factors for metabolic disorder of dairy cows. Oxidative stress can activate transcription factor nuclear factor kappa B (NF-κB), which lead to the upregulation of genes involved in inflammatory pathways. Thioredoxin-2 (TXN2) is a mitochondrial protein that regulates cellular redox by suppressing mitochondrial reactive oxygen species (ROS) generation in nonruminant, whereas the function of TXN2 in bovine adipocytes was unclear. Thus, the objective of this study was to evaluate how or by which mechanisms TXN2 regulates oxidative stress and NF-κB signaling pathway in bovine adipocytes. Bovine pre-adipocytes isolated from 5 healthy Holstein cows were differentiated and used for (1) treatment with different concentrations of hydrogen peroxide (H2O2; 0, 25, 50, 100, 200, or 400 μM) for 2 h; (2) transfection with or without TXN2 small interfering RNA (si-TXN2) for 48 h and then treated with or without 200 μM H2O2 for 2 h; (3) transfection with scrambled negative control siRNA (si-control) or si-TXN2 for 48 h, and then treatment with or without 10 mM N-acetylcysteine (NAC) for 2 h; (4) transfection with or without TXN2-overexpressing plasmid for 48 h and then treatment with or without 200 μM H2O2 for 2 h. High concentrations of H2O2 (200 and 400 μM) decreased protein and mRNA abundance of TXN2, reduced total antioxidant capacity (T-AOC) and ATP content in adipocytes. Moreover, 200 and 400 μM H2O2 reduced protein abundance of inhibitor of kappa B α (IκBα), increased phosphorylation of NF-κB and upregulated mRNA abundance of tumor necrosis factor-α (TNFA) and interleukin-1B (IL-1B), suggesting that H2O2-induced oxidative stress and activated NF-κB signaling pathway. Silencing of TXN2 increased intracellular ROS content, phosphorylation of NF-κB and mRNA abundance of TNFA and IL-1B, decreased ATP content and protein abundance of IκBα in bovine adipocytes. Knockdown of TXN2 aggravated H2O2-induced oxidative stress and inflammation. In addition, treatment with antioxidant NAC ameliorated oxidative stress and inhibited NF-κB signaling pathway in adipocytes transfected with si-TXN2. In bovine adipocytes treated with H2O2, overexpression of TXN2 reduced the content of ROS and elevated the content of ATP and T-AOC. Overexpression of TXN2 alleviated H2O2-induced inflammatory response in adipocytes, as demonstrated by decreased expression of phosphorylated NF-κB, TNFA, IL-1B, as well as increased expression of IκBα. Furthermore, the protein and mRNA abundance of TXN2 was lower in adipose tissue of dairy cows with clinical ketosis. Overall, our studies contribute to the understanding of the role of TXN2 in adipocyte oxidative stress and inflammatory response.

Enhancing bovine immune, antioxidant and anti-inflammatory responses with vitamins, rumen-protected amino acids, and trace minerals to prevent periparturient mastitis

Mastitis, the inflammatory condition of mammary glands, has been closely associated with immune suppression and imbalances between antioxidants and free radicals in cattle. During the periparturient period, dairy cows experience negative energy balance (NEB) due to metabolic stress, leading to elevated oxidative stress and compromised immunity. The resulting abnormal regulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS), along with increased non-esterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) are the key factors associated with suppressed immunity thereby increases susceptibility of dairy cattle to infections, including mastitis. Metabolic diseases such as ketosis and hypocalcemia indirectly contribute to mastitis vulnerability, exacerbated by compromised immune function and exposure to physical injuries. Oxidative stress, arising from disrupted balance between ROS generation and antioxidant availability during pregnancy and calving, further contributes to mastitis susceptibility. Metabolic stress, marked by excessive lipid mobilization, exacerbates immune depression and oxidative stress. These factors collectively compromise animal health, productive efficiency, and udder health during periparturient phases. Numerous studies have investigated nutrition-based strategies to counter these challenges. Specifically, amino acids, trace minerals, and vitamins have emerged as crucial contributors to udder health. This review comprehensively examines their roles in promoting udder health during the periparturient phase. Trace minerals like copper, selenium, and calcium, as well as vitamins; have demonstrated significant impacts on immune regulation and antioxidant defense. Vitamin B12 and vitamin E have shown promise in improving metabolic function and reducing oxidative stress followed by enhanced immunity. Additionally, amino acids play a pivotal role in maintaining cellular oxidative balance through their involvement in vital biosynthesis pathways. In conclusion, addressing periparturient mastitis requires a holistic understanding of the interplay between metabolic stress, immune regulation, and oxidative balance. The supplementation of essential amino acids, trace minerals, and vitamins emerges as a promising avenue to enhance udder health and overall productivity during this critical phase. This comprehensive review underscores the potential of nutritional interventions in mitigating periparturient bovine mastitis and lays the foundation for future research in this domain.

Association of vitamin D status with redox balance and insulin resistance and its predicting ability for subclinical pregnancy toxemia in pregnant sheep

The study aimed to evaluate the role of vitamin D on redox balance, insulin resistance and its predicting value for subclinical pregnancy toxemia (SPT) in pregnant ewes. At four weeks pre-lambing, fifteen healthy pregnant ewes were divided into two groups, ewes with sufficient vitamin D (25-hydroxy-vitamin D (25VitD) (SVD, n = 9) and ewes with insufficient 25VitD (ISVD, n = 6). Blood samples were collected at 4 weeks pre-lambing using modified frequently sampled intravenous glucose tolerance test for the estimation of various metabolites. The baseline glucose, insulin, non-esterified fatty acid (NEFA), fructosamine, beta-hydroxy butyric acid (β-BHA), calcium, phosphorus concentration and total oxidant status (TOS) did not differ significantly between the two groups, however, total antioxidant capacity (TAC) was significantly (p = 0.031) low in ISVD ewes. Area under the curve for glucose, insulin, elimination rate of glucose and peak insulin also did not differ significantly between the two groups. Correlation analysis revealed, positive association of 25VitD with fructosamine, calcium and TAC, and negative correlation with NEFA and TOS. Subsequent blood sampling at 2 weeks pre-lambing and at lambing showed significant difference in NEFA (p = 0.001), β-HBA (p = 0.001), and fructosamine(p = 0.012) between the two groups. A significant time x group interaction was observed in NEFA (p = 0.019), β-HBA (p = 0.031), and fructosamine (p = 0.026) concentration. The NEFA concentrations were increased and fructosamine decreased at 2 weeks pre-lambing and at lambing along with significantly increased β-HBA at 2 weeks pre-lambing in ISVD compared to SVD. Taking 0.8 mmol/L β-HBA as the cut off limit for SPT, ISVD ewes had higher odds of developing SPT two weeks prior to lambing (OD 16.00; p = 0.042) and at lambing (OD 10; p = 0.077). This study concludes that 25VitD significantly influence redox balance and energy profile and serves as a valuable predictor for SPT in pregnant sheep.

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.

Intramammary 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 treatments differentially increase serum calcium and milk cell gene expression

Intramammary 25-hydroxyvitamin D₃ (25D) and 1,25-dihydroxyvitamin D₃ (1,25D) treatments stimulate immune defenses of the mammary gland. We hypothesized 25D treatment, in contrast to 1,25D, would exert activity in the mammary gland without affecting serum calcium. The objective was to determine the effect of dose and source of intramammary vitamin D treatments on milk somatic cell gene expression and serum calcium. Twenty lactating Holstein cows with somatic cell count <200,000 cells/mL of milk were used for the experiment. Cows were blocked by somatic cell count and randomly assigned to 1 of 5 intramammary treatments (n = 4 cows/treatment): placebo control (CNTRL; 0.4% Tween 20 in phosphate-buffered saline), 100 μg of 25D, 500 μg of 25D, 10 μg of 1,25D, or 50 μg of 1,25D. Treatments were administered in 2 ipsilateral quarters after milking. Blood samples were collected at 0, 12, 24, and 48 h for measurement of Ca and 1,25D. Milk samples were collected from each quarter at 0, 6, 12, 24, and 48 h relative to the start of treatments for measurement of gene expression in milk somatic cells. The 1,25D treatments increased serum concentrations of 1,25D and Ca in a dose-dependent manner with maximum 1,25D and Ca concentrations of 199 ± 6 pg/mL and 2.73 ± 0.04 mM, respectively, observed for 50 μg of 1,25D cows compared with 59 ± 6 pg/mL and 2.54 mM, respectively, for CNTRL cows. The 25D treatments did not affect serum 1,25D and Ca compared with CNTRL. The 25D and 1,25D treatments increased mRNA transcripts for vitamin D 24-hydroxylase (CYP24A1), inducible nitric oxide synthase (NOS2A), and chemokine C-C motif ligand 5 (CCL5) in a dose-dependent manner. The 50 μg of 1,25D treatment resulted in the greatest CYP24A1 expression (303-fold relative to CNTRL) at 6 h but was not different from CNTRL at 24 h. In contrast, CYP24A1 was 57-fold greater for cows that received 500 μg of 25D compared with CNTRL at 24 h. In conclusion, intramammary 25D treatment is effective at regulating gene expression in the mammary gland without systemic effects on serum 1,25D and Ca that occur with intramammary 1,25D treatment.

Bovine Immunity and Vitamin D3: An Emerging Association in Johne's Disease

Mycobacterium avium subspecies paratuberculosis (MAP) is an environmentally hardy pathogen of ruminants that plagues the dairy industry. Hallmark clinical symptoms include granulomatous enteritis, watery diarrhea, and significant loss of body condition. Transition from subclinical to clinical infection is a dynamic process led by MAP which resides in host macrophages. Clinical stage disease is accompanied by dysfunctional immune responses and a reduction in circulating vitamin D3. The immunomodulatory role of vitamin D3 in infectious disease has been well established in humans, particularly in Mycobacterium tuberculosis infection. However, significant species differences exist between the immune system of humans and bovines, including effects induced by vitamin D3. This fact highlights the need for continued study of the relationship between vitamin D3 and bovine immunity, especially during different stages of paratuberculosis.

SBT (Composed of Panax ginseng and Aconitum carmichaeli) and Stigmasterol Enhances Nitric Oxide Production and Exerts Curative Properties as a Potential Anti-Oxidant and Immunity-Enhancing Agent

Immune dysregulation is a risk factor for several diseases, including infectious diseases. Immunostimulatory agents have been used for the treatment of immune dysregulation, but deleterious adverse effects have been reported. The present study aims to establish the anti-oxidant and immunity-enhancing effects of Sambu-Tang (SBT), composed of Panax ginseng and Aconitum carmichaeli, and stigmasterol (Stig), an active compound of SBT. Immune-related factors were analyzed in RAW264.7 macrophage cells, mouse primary splenocytes, and the serum and spleen of cyclophosphamide-induced immunosuppressed mice. Results showed that the production levels of nitric oxide (NO) and expression levels of inducible NO synthase and heme oxygenase-1 were increased following SBT or Stig treatment in RAW264.7 cells. SBT or Stig increased the production levels of G-CSF, IFN-γ, IL-12, IL-2, IL-6, and TNF-α and induced the activation of NF-κB in RAW264.7 cells. SBT or Stig promoted splenic lymphocyte proliferation and increased splenic NK cell cytotoxic activity. In addition, SBT or Stig enhanced the levels of IFN-γ, IL-12, IL-2, IL-6, or TNF-α in the serum and spleen of the immunosuppressed mice. SBT or Stig increased the superoxide dismutase activity in the spleen. Collectively, SBT and Stig possess anti-oxidant and immunomodulatory activities, so they may be considered effective natural compounds for the treatment of various symptoms caused by immune dysregulation.

Serum Vitamin D Is Associated with Antioxidant Potential in Peri-Parturient Cows

Dairy cows experience increased oxidative stress during periods of transition such as at the cessation of lactation and around the periparturient period, thus increasing disease risk. Despite routine supplementation of transition cow diets with certain vitamins in an attempt to mitigate oxidative stress, there is no currently available data directly linking vitamin supplementation with antioxidant potential (AOP) in transition cows. The objective of this study was to determine the association between serum vitamins and biomarkers of oxidative stress in healthy cows. Blood samples were collected from 240 cows at dry off (DO), close up (CU), and 2-10 days post-calving (DIM2-10). Blood samples were analyzed for vitamins (A, D, E), β-carotene, reactive oxygen species (ROS), and AOP. Spearman correlations and mixed linear regression models were used to assess associations between vitamins and measures of oxidant status. Vitamin D concentrations were positively associated with AOP at the CU and DIM2-10. Based on the positive association with AOP, additional in-vitro studies were conducted that showed vitamin D mitigated barrier integrity loss in endothelial cells during oxidative stress. These results indicate for the first time that vitamin D may have a role in promoting antioxidant potential in transition dairy cows.