Abstract
Studying host parasite interactions and their implications for evolution and ecology recently received increasing attention, particularly with regard to host physiology and immunity. Here we assess variation of urinary neopterin (uNEO), a marker of cellular immune activation and iummunosenescence, in response to age and anthelmintic treatment in semi-free ranging Barbary macaques (Macaca sylvanus). Urinary NEO levels were measured via enzyme-immunoassay from 179 urine samples of 43 individuals between 5–29 years of age. Efficiency of treatment was assessed by Mc Master flotation on repeated faecal samples, including 18 untreated individuals as control group. We used linear mixed models with age and parasite status as main effects, controlling for sex and physical condition, assessed through urinary C-Peptide-levels, with social group and ID as random factors. Urinary NEO levels significantly increased with age, suggesting that changes in aging Barbary macaque immune responses are consistent with immunosenescence described in human and nonhuman primates and can be detected via uNEO measurements. Anthelmintic treatment, however, had no influence on uNEO levels, potentially due to quick reinfections or attenuated immune responses in repeated infections. We conclude that uNEO is a potential non-invasive marker for immune function and particularly immunosenescence in wildlife.
Highlights
Lead to energy allocation away from reproduction[23]
In accordance with previous studies on human and nonhuman primates, aged Barbary macaques of our study groups showed higher uNEO levels compared to younger adult individuals
This leads us to conclude that semi-free ranging Barbary macaques, presumably faced with a more natural range of pathogens than are laboratory nonhuman primates, show signs of immunosenescence which can be measured by uNEO levels
Summary
Lead to energy allocation away from reproduction[23]. Using blood samples is highly efficient when studying immune responses on the molecular level and have generated major insights into host-parasite interactions[24] and the effects of intrinsic and extrinsic factors on immune responses and reactivity[10,25]. Since IFNγand NEO are closely linked functionally[28], similar patterns are expected for NEO in aging nonhuman primates This is supported by a recent study that reported a significant positive correlation between serum NEO levels and age in healthy macaques[26]. We capitalized on routine six-monthly anthelmintic treatment and assessed the impact of parasite clearance on uNEO levels in a cross-sectional design Since both arms of the immune system, Th1 and Th2 are mutually inhibitory[55], high levels of NEO represent an efficient Th1, and an inhibited Th2 response. Based on the findings of Ezenwa et al.[24,54], we predicted uNEO levels to be increased after treatment due to lack of immunomodulation by parasites
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