Chronic elevation of glucorticoids late in life generates long lasting changes in physiological state without a life history switch

Chronic stressors have profound impacts on phenotypes and life history strategies on the short term, but delayed effects of stress experienced late in life remain poorly investigated in wild populations. Here, we used a combined laboratory and field experiment to test if chronic stress late in life has immediate and delayed effects on physiological and demographic traits in the common lizard, Zootoca vivipara. We increased plasma corticosterone levels in adults and yearlings during three weeks of the post-reproductive season. We quantified immediate responses in the laboratory, delayed intra-generational effects in field enclosures one month and one year later during the next reproductive season, and delayed inter-generational effects in the first generation of offspring. Our phenotypic assays included metabolism, immune capacities, lipid metabolism and oxidative stress. Relative to placebos, lizards treated with corticosterone had higher body condition and lower oxidative damages but an increased skin swelling response directly after the manipulation. Delayed responses in field enclosures were of three types. First, we found catch-up growth for body mass such the placebos had similar body conditions one month after the laboratory manipulation. Second, we found persistent differences in oxidative damages during one month but not one year later. Third, during the next reproductive season, corticosterone-treated females had higher levels of plasma triglycerides, whereas corticosterone-treated individuals had a higher skin swelling response. We found no delayed inter-generational effects on demographic traits of offspring. Our study demonstrates the potential for long-lasting physiological consequences of chronic corticosterone enhancement despite no obvious changes in life history.

Age, sex, and nutritional status modify the CD4+ T-cell recovery rate in HIV-tuberculosis co-infected patients on combination antiretroviral therapy

BACKGROUND

Baseline age and combination antiretroviral therapy (cART) were examined as determinants of CD4+ T-cell recovery during 6 months of tuberculosis (TB) therapy with/without cART. It was determined whether this association was modified by patient sex and nutritional status.

METHODS

This longitudinal analysis included 208 immune-competent, non-pregnant, ART-naive HIV-positive patients from Uganda with a first episode of pulmonary TB. CD4+ T-cell counts were measured using flow cytometry. Age was defined as ≤24, 25-29, 30-34, and 35-39 vs. ≥40 years. Nutritional status was defined as normal (>18.5kg/m(2)) vs. underweight (≤18.5kg/m(2)) using the body mass index (BMI). Multivariate random effects linear mixed models were fitted to estimate differences in CD4+ T-cell recovery in relation to specified determinants.

RESULTS

cART was associated with a monthly rise of 15.7 cells/μl (p<0.001). Overall, age was not associated with CD4+ T-cell recovery during TB therapy (p = 0.655). However, among patients on cART, the age-associated CD4+ T-cell recovery rate varied by sex and nutritional status, such that age <40 vs. ≥40 years predicted superior absolute CD4+ T-cell recovery among females (p=0.006) and among patients with a BMI ≥18.5kg/m(2) (p<0.001).

CONCLUSIONS

TB-infected HIV-positive patients aged ≥40 years have a slower rate of immune restoration given cART, particularly if BMI is >18.5kg/m(2) or they are female. These patients may benefit from increased monitoring and nutritional support during cART.