Department of Physiological Sciences

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Browsing Department of Physiological Sciences by Author "Africa, Luan Dane"

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    HIV-1 associated neuroinflammation : effects of two complimentary medicines illustrated in an in vitro model of the blood-brain barrier
    (Stellenbosch : Stellenbosch University, 2014-12) Africa, Luan Dane; Smith, Carine; Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disorders (HAND) that are prevalent in late stage AIDS. ARV treatments are rolled out relatively late in the context of neuroinflammatory changes, so that their usefulness in directly preventing HAND is probably limited. It is common practice for HIV+ individuals in developing countries to make use of traditional/complimentary medicines. One such medicine is Sutherlandia frutescens - commonly consumed as a water infusion. We have also identified a new candidate complimentary medicine for use in this context - grape seed-derived proanthocyanidolic oligomers (PCO) have significant anti-inflammatory action in the peripheral compartment in the context of e.g. skeletal muscle injury, but have not been investigated in the context of either neuroinflammation or HIV/AIDS. Here the efficacy of these two substances as an anti-inflammatory modality in this context was investigated in an in vitro co-culture model of the blood-brain barrier (BBB). Methods: Single cultures of human astrocytes, HUVECs and primary human monocytes, as well as co-cultures (BBB), were stimulated with HIV-1 subtype B & C Tat protein and/or HL2/3 cell secretory proteins after pre-treatment with S. frutescens or PCO extracts. Effects of this pre-treatment on pro-inflammatory mediator expression and monocyte migration across the BBB were assessed. Results: In accordance with others, B Tat was more pro-inflammatory than C Tat, validating our model. S. frutescens decreased IL-1β secretion significantly (P<0.0001), but exacerbated both monocyte chemoattractant protein-1 (P<0001) – a major role player in HIV-associated neuroinflammation – and CD14+ monocyte infiltration across the BBB (P<0.01). PCO pre-treatment resulted in a significantly dampened IL-1β (P<0.0001) response to stimulation with HIV-associated proteins. In contrast to S. frutescens, PCO modulated monocyte chemoattractant protein-1 (P<0001) response and decreased capacity for CD14+ monocytes to migrate across the simulated BBB (P<0.0001). Additionally, PCO pre-treatment decreased both GFAP (P<0.001) and HSP-27 (P<0.001) expression in the astrocytes of the BBB. Conclusions: Current data illustrates that the combined use of HL2/3 cells and the simulated BBB presents an accurate, disease relevant in vitro model with which to study neuroinflammation in the context of HIV/AIDS. In addition, our results caution against the use of S. frutescens as anti-inflammatory modality at any stage post-HIV infection. Novel data presented here illustrate that PCO is able to blunt the MCP-1 and IL-1β response to HIV-1 proteins in single cultures of human astrocytes and HUVECs, as well as in an in vitro simulation of the BBB. In addition, PCO was able to limit monocyte transmigration across the simulated BBB in response to HIV-1 proteins generated by HL2/3 cells. This suggests that grape seed-derived PCO could be considered as complimentary anti-neuroinflammatory drug in the context of HIV/AIDS.
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    Sutherlandia frutescens may exacerbate HIV-associated neuroinflammation
    (BioMed Central, 2015-07-18) Africa, Luan Dane; Smith, Carine
    Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disorders (HAND) that are prevalent in late stage AIDS. Anti-retroviral (ARV) treatments are rolled out relatively late in the context of neuroinflammatory changes, so that their usefulness in directly preventing HAND is probably limited. It is common practice for HIV+ individuals in developing countries to make use of traditional medicines. One such medicine is Sutherlandia frutescens - commonly consumed as a water infusion. Here its efficacy as an anti-inflammatory modality in this context was investigated in an in vitro co-culture model of the blood–brain barrier (BBB). Methods: Single cultures of human astrocytes (HA), HUVECs and primary human monocytes, as well as co-cultures (BBB), were stimulated with HIV-1 subtype B & C Tat protein and/or HL2/3 cell secretory proteins after pre-treatment with S.frutescens extract. Effects of this pre-treatment on pro-inflammatory cytokine secretion and monocyte migration across the BBB were assessed. Results: In accordance with others, B Tat was more pro-inflammatory than C Tat, validating our model. S.frutescens decreased IL-1β secretion significantly (P < 0.0001), but exacerbated both monocyte chemoattractant protein-1 (P < 0001) – a major role player in HIV-associated neuroinflammation – and CD14+ monocyte infiltration across the BBB (P < 0.01). Conclusions: Current data illustrates that the combined use of HL2/3 cells and the simulated BBB presents an accurate, physiologically relevant in vitro model with which to study neuroinflammation in the context of HIV/AIDS. In addition, our results caution against the use of S.frutescens as anti-inflammatory modality at any stage post-HIV infection.