Glucose Availability and AMP-Activated Protein Kinase Link Energy Metabolism and Innate Immunity in the Bovine Endometrium

Defences against the bacteria that usually infect the endometrium of postpartum cattle are impaired when there is metabolic energy stress, leading to endometritis and infertility. The endometrial response to bacteria depends on innate immunity, with recognition of pathogen-associated molecular patterns stimulating inflammation, characterised by secretion of interleukin (IL)-1β, IL-6 and IL-8. How metabolic stress impacts tissue responses to pathogens is unclear, but integration of energy metabolism and innate immunity means that stressing one system might affect the other. Here we tested the hypothesis that homeostatic pathways integrate energy metabolism and innate immunity in bovine endometrial tissue. Glucose deprivation reduced the secretion of IL-1β, IL-6 and IL-8 from ex vivo organ cultures of bovine endometrium challenged with the pathogen-associated molecular patterns lipopolysaccharide and bacterial lipopeptide. Endometrial inflammatory responses to lipopolysaccharide were also reduced by small molecules that activate or inhibit the intracellular sensor of energy, AMP-activated protein kinase (AMPK). However, inhibition of mammalian target of rapamycin, which is a more global metabolic sensor than AMPK, had little effect on inflammation. Similarly, endometrial inflammatory responses to lipopolysaccharide were not affected by insulin-like growth factor-1, which is an endocrine regulator of metabolism. Interestingly, the inflammatory responses to lipopolysaccharide increased endometrial glucose consumption and induced the Warburg effect, which could exacerbate deficits in glucose availability in the tissue. In conclusion, metabolic energy stress perturbed inflammatory responses to pathogen-associated molecular patterns in bovine endometrial tissue, and the most fundamental regulators of cellular energy, glucose availability and AMPK, had the greatest impact on innate immunity

Potential of lactoferrin to prevent antibiotic-induced Clostridium difficile infection

Objectives: C. difficile infection (CDI) is a global healthcare problem. Recent evidence suggests that the availability of iron may be important for C. difficile growth. This study evaluated the comparative effects of iron-depleted (1% Fe3+ saturated) bovine apo-lactoferrin (apo-bLf) and iron-saturated (85% Fe3+ saturated) bovine holo-lactoferrin (holo-bLf) in a human in vitro gut model that simulates CDI. Methods: Two parallel triple-stage chemostat gut models were inoculated with pooled human faeces and spiked with C. difficile spores (strain 027 210, PCR ribotype 027). Holo- or apo-bLf was instilled (5mg/mL, once daily) for 35 days. After 7 days, clindamycin was instilled (33.9mg/L, four times daily) to induce simulated CDI. Indigenous microflora populations, C. difficile total counts and spores , cytotoxin titres, short-chain fatty acids, biometals, lactoferrin, and iron content of lactoferrin were monitored daily. Results: In the apo-bLf model, germination of C. difficile spores occurred 6 days post-clindamycin, followed by rapid vegetative cell proliferation and detectable toxin. By contrast, in the holo-bLf model, only a modest vegetative cell population was observed until 16 days post-antibiotic. Notably, no toxin was detected in this model. In separate batch culture experiments, holo-bLf prevented C. difficile vegetative cell growth and toxin production, whereas apo-bLf and iron alone did not. Conclusions: Holo-bLf but not apo-bLf delayed C. difficile growth and prevented toxin production in a human gut model of CDI. This inhibitory effect may be iron-independent. These observations suggest that bLf in its iron-saturated state could be used as a novel preventative or treatment strategy for CDI

Surviving in isolation: genetic variation, bottlenecks and reproductive strategies in the Canarian endemic Limonium macrophyllum (Plumbaginaceae)

Oceanic archipelagos are typically rich in endemic taxa, because they offer ideal conditions for diversification and speciation in isolation. One of the most remarkable evolutionary radiations on the Canary Islands comprises the 16 species included in Limonium subsection Nobiles, all of which are subject to diverse threats, and legally protected. Since many of them are single-island endemics limited to one or a few populations, there exists a risk that a loss of genetic variation might limit their longterm survival. In this study, we used eight newly developed microsatellite markers to characterize the levels of genetic variation and inbreeding in L. macrophyllum, a species endemic to the North-east of Tenerife that belongs to Limonium subsection Nobiles. We detected generally low levels of genetic variation over all populations (HT = 0.363), and substantial differentiation among populations (FST = 0.188;RST = 0.186) coupled with a negligible degree of inbreeding (F = 0.042). Obligate outcrossing may have maintained L. macrophyllum relatively unaffected by inbreeding despite the species’ limited dispersal ability and the genetic bottlenecks likely caused by a prolonged history of grazing. Although several factors still constitute a risk for the conservation of L. macrophyllum, the lack of inbreeding and the recent positive demographic trends observed in the populations of this species are factors that favour its future persistence

Effect of GnRH and PGF₂ alpha on Reproduction in Postpartum Dairy Cows

Thirty dairy cows were injected intramuscularly with 100 mcg gonadotropin releasing hormone ( GnRH) at 10-16 days postpartum followed by 25 mg. prostaglandin F2 alpha (PGF2 alpha) 14 days later. Twenty-nine other dairy cows (controls) were treated in a similar manner but saline was injected rather than GnRH or PGF2 alpha. Blood samples were taken for progresterone analysis before each injection and approximately 30 hours after the PGF2 alpha or second saline injection. The reproductive tract was evaluated by rectal palpation at the time of each injection. Only cows without obvious uterine infection were used and any pathological conditions that developed subsequently were treated after the experimental period. The cows were inseminated at the first estrus after 135-40 days postpartum.</jats:p