Rates of change in liver copper concentration in cattle given a copper-deficient diet, with or without pre-treatment with tetrathiomolybdate, for evaluation of two parenteral copper supplements

Copper Promotes LPS-Induced Inflammation via the NF-кB Pathway in Bovine Macrophages

Inflammation is a complex physiological process that enables the clearance of pathogens and repairing damaged tissues. Elevated serum copper concentration has been reported in cases of inflammation, but the role of copper in inflammatory responses remains unclear. This study used bovine macrophages to establish lipopolysaccharide (LPS)-induced inflammation model. There were five groups in the study: a group treated with LPS (100 ng/ml), a group treated with either copper chelator (tetrathiomolybdate, TTM) (20 μmol) or CuSO4 (25 μmol or 50 μmol) after LPS stimulation, and a control group. Copper concentrations increased in macrophages after the LPS treatment. TTM decreased mRNA expression of pro-inflammatory factors (IL-1β, TNF-α, IL-6, iNOS, and COX-2), whereas copper supplement increased them. Compared to the control group, TLP4 and MyD88 protein levels were increased in the TTM and copper groups. However, TTM treatment decreased p-p65 and increased IкB-α while the copper supplement showed reversed results. In addition, the phagocytosis and migration of bovine macrophages decreased in the TTM treatment group while increased in the copper treatment groups. Results mentioned above indicated that copper could promote the LPS-induced inflammatory response in bovine macrophages, promote pro-inflammatory factors by activating the NF-кB pathway, and increase phagocytosis capacity and migration. Our study provides a possible targeted therapy for bovine inflammation.

Liver copper concentration dynamics with different methods of injectable copper supplementation in dairy cows in New Zealand

AIMS

To compare the responses of liver Cu concentrations in dairy cows between three forms of injectable Cu supplementation and a negative control group.

METHODS

Across two dairy farms in North Canterbury, New Zealand, 80 mid-lactation dairy cows (n = 28 and 52 per farm) were randomly allocated to four treatment groups: (a) 100-mg or (b) 200-mg dose of Cu administered as Ca Cu EDTA; (c) 75-mg dose of Cu as disodium Cu EDTA combined with Se, Zn, and Mn; or (d) no treatment (negative control). Each treatment group contained 20 cows. Groups were balanced for age, plasma Cu and pre-treatment liver Cu concentration. Blood samples and liver biopsies were collected prior to treatment. Six liver biopsies were performed on the same cow over a period of 70 days and the concentration of liver Cu was measured over time and compared to pre-treatment baseline. A mixed, multivariable, linear regression model was constructed to determine the effect of treatment on the change in liver Cu concentration compared to pre-treatment concentrations, accounting for repeated measurements taken from each cow.

RESULTS

There was a difference in the distribution of pre-treatment liver Cu concentration between farms (p = 0.008), with medians of 1,400 (IQR 1,200-1,625) and 1,050 (IQR 805-1,425) µmol/kg on Farms 1 and 2, respectively. There was an interaction between treatment group, study day, and farm, with a treatment effect confirmed only on Farm 2. In the final model, the predicted change in liver Cu concentration (compared to pre-treatment concentrations) among cows on Farm 2 that were treated with 200 mg of Ca Cu EDTA was significantly higher than that of control cows on Days 3, 14, 28 and 42, peaking on Day 14 with a difference of 325.35 (95% CI = 97.00-554.03) µmol/kg. The study found no associations between changes in liver Cu concentration and age or prior plasma Cu concentration. The intraclass correlation coefficient was 0.57 (95% CI = 0.45-0.66), indicating the proportion of variability in changes in liver Cu concentration attributable to inter-cow variation.

CONCLUSIONS AND CLINICAL RELEVANCE

This study shows there are differences in response to injectable Cu supplementation at the farm level and wide variation in liver Cu among cows from the same farm. On one farm, a 200-mg dosage of Ca Cu EDTA significantly increased liver Cu concentration for at least 42 days.

Copper Supplementation, A Challenge in Cattle

Ensuring adequate copper supplementation in ruminants is a challenging task due to the complexity of copper metabolism in these animals. The three-way interaction between copper, molybdenum and sulphur (Cu-Mo-S) in the rumen makes ruminants, particularly cattle, very susceptible to suffering from secondary copper deficiency. Paradoxically, excessive copper storage in the liver to prevent deficiency becomes a hazard when ruminants are fed copper-supplemented diets even slightly above requirements. While cattle were traditionally thought to be relatively tolerant of copper accumulation, and reports of copper poisoning were until recently somewhat rare, in recent years an increased number of episodes/outbreaks of copper toxicity in cattle, particularly in dairy cattle, have been reported worldwide. The growing number of lethal cases reported seems to indicate that copper intoxication is spreading silently in dairy herds, urging the development of strategies to monitor herd copper status and improve farmers' awareness of copper toxicity. In fact, monitoring studies carried out on numerous samples collected from culled animals in slaughterhouses and/or diagnostic laboratories have demonstrated that large numbers of animals have hepatic copper concentrations well above adequate levels in many different countries. These trends are undoubtedly due to copper supplementation aimed at preventing copper deficiency, as dietary copper intake from pasture alone is unlikely to cause such high levels of accumulation in liver tissue. The reasons behind the copper overfeeding in cattle are related both to a poor understanding of copper metabolism and the theory of "if adding a little produces a response, then adding a lot will produce a better response". Contrary to most trace elements, copper in ruminants has narrow margins of safety, which must also be formulated considering the concentrations of copper antagonists in the diet. This review paper aims to provide nutritionists/veterinary practitioners with the key points about copper metabolism in cattle to guarantee an adequate copper supply while preventing excessive hepatic copper loading, which requires à la carte copper supplementation for each herd.

Effect of sodium molybdate supplementation on high concentrations of Cu in liver of yearling bulls

AIM

To determine the impact of sodium molybdate treatment, given weekly, on concentrations of Cu in liver, activity of liver enzymes, and weight gain over 4 weeks, in yearling bulls with elevated concentrations of Cu in liver.

METHODS

The study was carried on two commercial grazing farms in the Otago region of New Zealand in yearling Friesian bulls (n=150 on Farm A and n=49 on Farm B) with mean concentration of Cu in liver >3,000 µmol/kg fresh weight. On Day 0, all animals were weighed and half were systematically allocated to treatment with sodium molybdate (3 mg/kg liveweight on Farm A and 7 mg/kg liveweight on Farm B); the remainder received no treatment (Control). Sodium molybdate was given as a drench weekly for 4 weeks and all animals were weighed again on Day 28. Ten animals on each farm (five from each treatment group) were systematically selected for blood sampling and liver biopsies on Days 0 and 28. Samples were analysed for concentrations of Cu in plasma, vitamin B₁₂ in serum, activities of γ-glutamyl transferase, aspartate aminotransferase and glutamate dehydrogenase in serum, and concentrations of Cu and vitamin B₁₂ in liver. Separate multivariable linear models were used to compare the change in outcome variables between Days 0 and 28 between bulls that had been drenched with sodium molybdate or not.

RESULTS

On Farm A, mean concentrations of Cu in liver on Day 28, as a percentage of concentrations on Day 0, for the control group was 55 (95% CI=40-73)% and for the treatment group was 73 (95% CI=43-111)%. On Farm B, the equivalent mean for the control group was 75 (95% CI=42-131)% and for the treatment group was 85 (95% CI=38-134)%. The multivariable linear models indicated that the changes in concentrations of Cu in liver, activities of liver enzymes and weight gain between Days 0 and 28 did not differ between the bulls treated or not with sodium molybdate (p>0.18).

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with sodium molybdate in one bolus at weekly intervals for 4 weeks did not affect concentrations of Cu in liver, activity of liver enzymes or weight gain in animals with high concentrations of Cu liver on two farms.

Copper imbalances in ruminants and humans: unexpected common ground

Ruminants are more vulnerable to copper deficiency than humans because rumen sulfide generation lowers copper availability from forage, increasing the risk of conditions such as swayback in lambs. Molybdenum-rich pastures promote thiomolybdate (TM) synthesis and formation of unabsorbable Cu-TM complexes, turning risk to clinical reality (hypocuprosis). Selection pressures created ruminant species with tolerance of deficiency but vulnerability to copper toxicity in alien environments, such as specific pathogen-free units. By contrast, cases of copper imbalance in humans seemed confined to rare genetic aberrations of copper metabolism. Recent descriptions of human swayback and the exploratory use of TM for the treatment of Wilson's disease, tumor growth, inflammatory diseases, and Alzheimer's disease have created unexpected common ground. The incidence of pre-hemolytic copper poisoning in specific pathogen-free lambs was reduced by an infection with Mycobacterium avium that left them more responsive to treatment with TM but vulnerable to long-term copper depletion. Copper requirements in ruminants and humans may need an extra allowance for the "copper cost" of immunity to infection. Residual cuproenzyme inhibition in TM-treated lambs and anomalies in plasma copper composition that appeared to depend on liver copper status raise this question "can chelating capacity be harnessed without inducing copper-deficiency in ruminants or humans?" A model of equilibria between exogenous (TM) and endogenous chelators (e.g., albumin, metallothionein) is used to predict risk of exposure and hypocuprosis; although risk of natural exposure in humans is remote, vulnerability to TM-induced copper deficiency may be high. Biomarkers of TM impact are needed, and copper chaperones for inhibited cuproenzymes are prime candidates.