Dataset Information

Aging dysregulates neutrophil extracellular trap formation in response to HIV in blood and genital tissues.

ABSTRACT: Women acquire HIV through sexual transmission, with increasing incidence in women >50 years old. Identifying protective mechanisms in the female genital tract (FGT) is important to prevent HIV-acquisition in women as they age. Human genital and blood neutrophils inactivate HIV by releasing neutrophil extracellular traps (NETs), an innate protective mechanism against HIV-infection. However, how NET formation is triggered by HIV in different tissues and whether this mechanism is affected by aging remain unknown. We demonstrate that the mechanisms that trigger NET release in response to HIV are different in blood and genital tissues, and that NET release decreases with aging. In blood neutrophils, HIV stimulation independently activated calcium pathways and endosomal TLR8, but aging reduced calcium responses, resulting in delayed NET release. In contrast, calcium responses were absent in genital neutrophils and NET release was triggered preferentially through TLR8 activation, but aging impaired this pathway. HIV induced NET formation through non-lytic pathways in blood and FGT neutrophils, except for a small subset of NETs that incorporated annexin V and lactoferrin predominantly in blood, suggesting proinflammatory and lytic NET release. Our findings demonstrate that blood neutrophils cannot model genital neutrophil responses which has important implications to understanding protection against HIV acquisition.

SUBMITTER: Moreno de Lara L

PROVIDER: S-EPMC10684664 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Aging dysregulates neutrophil extracellular trap formation in response to HIV in blood and genital tissues.

Moreno de Lara Laura L Werner Alexandra A Borchers Anna A Carrillo-Salinas Francisco J FJ Marmol Wendelin W Parthasarathy Siddharth S Iyer Vidya V Vogell Alison A Illanes Diego D Abadía-Molina Ana C AC Ochsenbauer Christina C Wira Charles R CR Rodriguez-Garcia Marta M

Frontiers in immunology 20231115

Women acquire HIV through sexual transmission, with increasing incidence in women >50 years old. Identifying protective mechanisms in the female genital tract (FGT) is important to prevent HIV-acquisition in women as they age. Human genital and blood neutrophils inactivate HIV by releasing neutrophil extracellular traps (NETs), an innate protective mechanism against HIV-infection. However, how NET formation is triggered by HIV in different tissues and whether this mechanism is affected by aging ...[more]

PMID: 38035114

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Project description:Neutrophils undergo a unique form of cell death to generate neutrophil extracellular traps (NETs). It is well established that citrullination of histones (e.g., CitH3) facilitates chromatin decondensation during NET formation (NETosis), particularly during calcium-induced NETosis that is independent of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activation. However, the importance of other forms of histone modifications in NETosis has not been established. We considered that acetylation of histones would also facilitate NETosis. To test this hypothesis, we induced NOX-dependent NETosis in human neutrophils with phorbol myristate acetate or lipopolysaccharide (from Escherichia coli 0128), and NOX-independent NETosis with calcium ionophores A23187 or ionomycin (from Streptomycesconglobatus) in the presence or absence of two pan histone deacetylase inhibitors (HDACis), belinostat and panobinostat (within their half maximal inhibitory concentration (IC50) range). The presence of these inhibitors increased histone acetylation (e.g., AcH4) in neutrophils. Histone acetylation was sufficient to cause a significant increase (~20%) in NETosis in resting neutrophils above baseline values. When acetylation was promoted during NOX-dependent or -independent NETosis, the degree of NETosis additively increased (~15⁻30%). Reactive oxygen species (ROS) production is essential for baseline NETosis (mediated either by NOX or mitochondria); however, HDACis did not promote ROS production. The chromatin decondensation step requires promoter melting and transcriptional firing in both types of NETosis; consistent with this point, suppression of transcription prevented the NETosis induced by the acetylation of histones. Collectively, this study establishes that histone acetylation (e.g., AcH4) promotes NETosis at baseline, and when induced by both NOX-dependent or -independent pathway agonists, in human neutrophils. Therefore, we propose that acetylation of histone is a key component of NETosis.

Project description:BackgroundNeutrophils are key players in innate immunity, forming neutrophil extracellular traps (NETs) to defend against infections. However, excess NET formation is implicated in inflammatory conditions such as sepsis and immunothrombosis. Studying NET formation in isolated neutrophils provides important mechanistic insights but does not reflect the complexity of immune interactions in whole blood, limiting our understanding of neutrophil responses.MethodsThis study investigates chromatin accessibility changes using Assay for Transposase-Accessible Chromatin with sequencing (ATAC-Seq) during phorbol 12-myristate 13-acetate (PMA) induced NET formation in whole blood. We compared chromatin accessibility patterns in neutrophils following PMA treatment in isolation and whole blood to assess the impact of other immune cells and signaling environment.ResultsWhole blood PMA stimulation elicited consistent chromatin accessibility changes across donors, demonstrating organized chromatin decondensation during NET formation. The chromatin response was characterized by increased accessibility in genomic regions enriched for immune-specific pathways, highlighting the role of immune cell interactions in NET formation. Differentially accessible regions (DARs) present following PMA induction in whole blood and isolated neutrophils showed greater association with NET-related and inflammatory transcription factors, while DARs specific to isolated neutrophils showed fewer relevant motifs. Pathway analysis indicated that whole blood responses involved more robust activation of immune-specific pathways, such as interleukin and cytokine signaling, compared to isolated neutrophils.ConclusionsOur findings underscore the importance of studying NET formation within a whole blood environment to capture the complexity of neutrophil responses and immune cell interactions. This understanding is crucial for identifying effective therapeutic targets in NET-associated inflammatory diseases.

Dataset Information

Aging dysregulates neutrophil extracellular trap formation in response to HIV in blood and genital tissues.

Publications

Aging dysregulates neutrophil extracellular trap formation in response to HIV in blood and genital tissues.

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