Within- and across-colony effects of hyperpolyandry on immune function and body condition in honey bees (Apis mellifera).

Honey bees (Apis mellifera) have become a model system for studies on the influence of genetic diversity on disease. Honey bee queens mate with a remarkably high number of males-up to 29 in the current study-from which they produce a colony of genetically diverse daughter workers. Recent evidence suggests a significant benefit of intracolony genetic diversity on disease resistance. Here, we explored the relationship between the level of genetic diversity and multiple physiological mechanisms of cellular and humoral immune defense (encapsulation response and phenoloxidase activity). We also investigated an effect of genetic diversity on a measure of body condition (fat body mass). While we predicted that mean colony phenoloxidase activity, encapsulation response, and fat body mass would show a positive relationship with increased intracolonial genetic diversity, we found no significant relationship between genetic diversity and these immune measures, and found no consistent effect on body condition. These results suggest that high genetic diversity as a result of extreme polyandry may have little bearing on the physiological mechanisms of immune function at naturally occurring mating levels in honey bees.

Genetic, individual, and group facilitation of disease resistance in insect societies.

In this review, we provide a current reference on disease resistance in insect societies. We start with the genetics of immunity in the context of behavioral and physiological processes and scale up levels of biological organization until we reach populations. A significant component of this review focuses on Apis mellifera and its role as a model system for studies on social immunity. We additionally review the models that have been applied to disease transmission in social insects and elucidate areas for future study in the field of social immunity.

The ontogeny of immunity: development of innate immune strength in the honey bee (Apis mellifera).

Honey bees (Apis mellifera) are of vital economic and ecological importance. These eusocial animals display temporal polyethism, which is an age-driven division of labor. Younger adult bees remain in the hive and tend to developing brood, while older adult bees forage for pollen and nectar to feed the colony. As honey bees mature, the types of pathogens they experience also change. As such, pathogen pressure may affect bees differently throughout their lifespan. We provide the first direct tests of honey bee innate immune strength across developmental stages. We investigated immune strength across four developmental stages: larvae, pupae, nurses (1-day-old adults), and foragers (22-30 days old adults). The immune strength of honey bees was quantified using standard immunocompetence assays: total hemocyte count, encapsulation response, fat body quantification, and phenoloxidase activity. Larvae and pupae had the highest total hemocyte counts, while there was no difference in encapsulation response between developmental stages. Nurses had more fat body mass than foragers, while phenoloxidase activity increased directly with honey bee development. Immune strength was most vigorous in older, foraging bees and weakest in young bees. Importantly, we found that adult honey bees do not abandon cellular immunocompetence as has recently been proposed. Induced shifts in behavioral roles may increase a colony's susceptibility to disease if nurses begin foraging activity prematurely.

A Darwinian approach to Huntington's disease: subtle health benefits of a neurological disorder.

Huntington's disease (HD) is a neurodegenerative disorder that, unlike most autosomal dominant disorders, is not being selected against. One explanation for the maintenance of the mutant HD allele is that it is transparent to natural selection because disease symptoms typically occur subsequent to an individual's peak reproductive years. While true, this observation does not explain the population-level increase in HD. The increase in HD is at least partly the result of enhanced fitness: HD+ individuals have more offspring than unaffected relatives. This phenomenon has previously been explained as the result of elevated promiscuity of HD+ individuals. For this to be true, disease symptoms must be expressed during the otherwise asymptomatic peak reproductive years and promiscuity must increase offspring production; however, neither prediction is supported by data. Instead, new data suggest that the mutant HD allele bestows health benefits on its carriers. HD+ individuals show elevated levels of the tumor suppressor protein p53 and experience significantly less cancer than unaffected siblings. We hypothesize that the mutant HD allele elevates carriers' immune activity and thus HD+ individuals are, on average, healthier than HD- individuals during reproductive years. As health and reproductive output are positively related, data suggest a counterintuitive relationship: health benefits may lead to an increased prevalence of Huntington's disease.

Susceptibility and behavioral responses of the dampwood termite Zootermopsis angusticollis to the entomopathogenic nematode Steinernema carpocapsae.

Termites exploit microbially rich resources such as decayed wood and soil that are colonized by potentially pathogenic and parasitic fungi, bacteria, viruses, and nematodes. In colonies composed of thousands of individuals, the risk of infection among nestmates is significant, and individual and social behavior could involve various adaptations to resist disease and parasitism. Here we show that the dampwood termite Zootermopsis angusticollis (Hagen) exhibits a dosage dependent susceptibility to the soil nematode Steinernema carpocapsae (Weiser) (Mexican strain) and that this social insect significantly alters its behavior in response to this entomopathogenic roundworm. Relative to their baseline behavior, termites exposed to infective juveniles increased the frequency and duration of allogrooming and vibratory displays as well as two other novel behaviors, abdominal tip-raising and self-scratching. Whereas the first two behaviors likely reflect general adaptations to reduce susceptibility to a variety of pathogens and parasites, the latter behaviors might be specific to nematodes because they have never been observed in Z. angusticollis in any other pathogenic context. Our results support the hypotheses that behavioral responses in termites are important in the control of pathogenic and parasitic microorganisms and that termite susceptibility is socially mediated.

The discovery of 6-[2-(5-chloro-2-{[(2,4-difluorophenyl)methyl]oxy}phenyl)-1-cyclopenten-1-yl]-2-pyridinecarboxylic acid, GW848687X, a potent and selective prostaglandin EP1 receptor antagonist for the treatment of inflammatory pain.

The discovery of a series of selective EP1 receptor antagonists based on a 1,2-diarylcyclopentene template is described. After defining the structural requirements for EP1 potency and selectivity, heterocyclic rings were incorporated to reduce logD and improve in vitro pharmacokinetic properties. The 2,6-substituted pyridines and pyridazines gave an appropriate balance of potency, in vivo pharmacokinetic properties and a low potential for inhibiting a range of CYP450 enzymes. From this series, GW848687X was shown to have an excellent profile in models of inflammatory pain and was selected as a development candidate.

5-aminosalicylate therapy is associated with higher 6-thioguanine levels in adults and children with inflammatory bowel disease in remission on 6-mercaptopurine or azathioprine.

BACKGROUND: Small uncontrolled trials have suggested that 5-aminosalicylate (5-ASA) medications increase 6-thioguanine nucleotide (6-TGn) levels in adults with Crohn's disease (CD) on azathioprine (AZA) or 6-mercaptopurine (6-MP), presumably through the inhibition of thiopurine methyltransferase (TPMT). We tested the theory that coadministration of 5-ASA agents with AZA/6-MP results in higher 6-TGn levels in a large cohort of children and adults with CD or ulcerative colitis (UC). METHODS: A retrospective cohort study identified all children and adults treated for IBD with AZA/6-MP at 2 tertiary medical centers. Patients were included if their TPMT genotype was known and 6-TGn and 6-methymercaptopurine (6-MMP) levels had been obtained after 3 months of clinical remission at a stable dose of AZA/6-MP. 6-TGn and 6-MMP levels were compared between patients taking and those not taking 5-ASA medications through the use of linear regression models to identify and adjust for potentially confounding variables. RESULTS: Of the 126 patients included, 88 were taking 5-ASA medications. Patients on 5-ASA agents had higher mean 6-TGn levels after adjustment for confounding variables (Delta6-TGn, 47.6 +/- 21.8 pmol/8 x 10 red blood cells; P = 0.03). CD and TPMT heterozygosity was independently associated with higher 6-TGn levels (P = 0.01 and P = 0.03, respectively). 5-ASA exposure was not associated with a change in 6-MMP levels. CONCLUSIONS: We found that 5-ASA therapy is associated with higher 6-TGn levels in children and adults with IBD on 6-MP/AZA. TPMT inhibition may not explain this effect because 5-ASA exposure did not affect 6-MMP levels. The observed association of CD with higher 6-TGn levels is novel and needs to be verified in prospective studies.