Objective In sub-Saharan Africa, HIV-exposed uninfected (HEU) infants have higher morbidity and mortality than HIV-unexposed infants. To evaluate whether immune dysfunction contributes to this vulnerability of HEU infants, we conducted a longitudinal, observational cohort study to assess T-cell immune responses to infant vaccines (Mycobacterium bovis BCG and acellular pertussis) and staphylococcal enterotoxin B (SEB). In total, 46 HEU and 46 HIV-unexposed infants were recruited from Khayelitsha, Cape Town. Methods Vaccine-specific T-cell proliferation (Ki67 expression) and intracellular expression of four cytokines [interferon-γ, interleukin (IL)-2, IL-13 and IL-17] were measured after whole blood stimulation with antigens at 6 and 14 weeks of age. Results HEU infants demonstrated elevated BCG-specific CD4+ and CD8+ T-cell proliferative responses at 14 weeks (P = 0.041 and 0.002, respectively). These responses were significantly increased even after adjusting for birth weight, feeding mode and gestational age. Similar to BCG, increased CD4+ and CD8+ T-cell proliferation was evident in response to SEB stimulation (P = 0.004 and 0.002, respectively), although pertussis-specific T cells proliferated comparably between the two groups. Within HEU infants, maternal CD4+ cell count and length of antenatal antiretroviral exposure had no effect on T-cell proliferation to BCG or SEB. HIV exposure significantly diminished measurable cytokine polyfunctionality in response to BCG, Bordetella pertussis and SEB stimulation. Conclusion These data show for the first time, when adjusting for confounders, that exposure to HIV in utero is associated with significant alterations to CD4+ and CD8+T-cell immune responses in infants to vaccines and nonspecific antigens.
In settings with universal antiretroviral coverage and high breastfeeding rates, breastfeeding mitigates the effects of in-utero HIV exposure among infants during the first year of life. These findings support previous recommendations for exclusive breastfeeding among HIV-infected women and highlight the role that breastfeeding plays on the health of infants in settings where exclusive breastfeeding is not always feasible or where replacement feeding is recommended.
Background and Objective Semantic memory measures may be useful in tracking and predicting progression of Alzheimer disease. We investigated relationships among semantic memory tasks and their 1-year predictive value in women with Alzheimer disease. Methods We conducted secondary analyses of a randomized clinical trial of raloxifene in 42 women with late-onset mild-to-moderate Alzheimer disease. We assessed semantic memory with tests of oral confrontation naming, category fluency, semantic recognition and semantic naming, and semantic density in written narrative discourse. We measured global cognition (Alzheimer Disease Assessment Scale, cognitive subscale), dementia severity (Clinical Dementia Rating sum of boxes), and daily function (Activities of Daily Living Inventory) at baseline and 1 year. Results At baseline and 1 year, most semantic memory scores correlated highly or moderately with each other and with global cognition, dementia severity, and daily function. Semantic memory task performance at 1 year had worsened one-third to one-half standard deviation. Factor analysis of baseline test scores distinguished processes in semantic and lexical retrieval (semantic recognition, semantic naming, confrontation naming) from processes in lexical search (semantic density, category fluency).The semantic–lexical retrieval factor predicted global cognition at 1 year. Considered separately, baseline confrontation naming and category fluency predicted dementia severity, while semantic recognition and a composite of semantic recognition and semantic naming predicted global cognition. No individual semantic memory test predicted daily function. Conclusions Semantic–lexical retrieval and lexical search may represent distinct aspects of semantic memory. Semantic memory processes are sensitive to cognitive decline and dementia severity in Alzheimer disease.
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