Inhibiting KDM6A Demethylase Represses Long Non-Coding RNA Hotairm1 Transcription in MDSC During Sepsis.

Myeloid-derived suppressor cells (MDSCs) prolong sepsis by promoting immunosuppression. We reported that sepsis MDSC development requires long non-coding RNA Hotairm1 interactions with S100A9. Using a mouse model that simulates the immunobiology of sepsis, we find that histone demethylase KDM6A promotes Hotairm1 transcription by demethylating transcription repression H3K27me3 histone mark. We show that chemical targeting of KDM6A by GSK-J4 represses Hotairm1 transcription, which coincides with decreases in transcription activation H3K4me3 histone mark and transcription factor PU.1 binding to the Hotairm1 promoter. We further show that immunosuppressive IL-10 cytokine promotes KDM6A binding at the Hotairm1 promoter. IL-10 knockdown repletes H3K27me3 and reduces Hotairm1 transcription. GSK-J4 treatment also relocalizes nuclear S100A9 protein to the cytosol. To support translation to human sepsis, we demonstrate that inhibiting H3K27me3 demethylation by KDM6A ex vivo in MDSCs from patients with protracted sepsis decreases Hotairm1 transcription. These findings suggest that epigenetic targeting of MDSCs in human sepsis might resolve post-sepsis immunosuppression and improve sepsis survival.

KDM6A Lysine Demethylase Directs Epigenetic Polarity of MDSCs during Murine Sepsis.

Sepsis-induced myeloid-derived suppressor cells (MDSCs) increase mortality risk. We previously identified that long non-coding RNA Hotairm1 supports myeloid precursor shifts to Gr1+CD11b+ MDSCs during mouse sepsis. A major unanswered question is what molecular processes control Hotairm1 expression. In this study, we found by a genetic deletion that a specific PU.1-binding site is indispensable in controlling Hotairm1 transcription. We then identified H3K4me3 and H3K27me3 at the PU.1 site on the Hotairm1 promoter. Controlling an epigenetic switch of Hotairm1 transcription by PU.1 was histone KDM6A demethylase for H3K27me3 that derepressed its transcription with possible contributions from Ezh2 methyltransferase for H3K27me3. KDM6A knockdown in MDSCs increased H3K27me3, decreased H3K4me3, and inhibited Hotairm1 transcription activation by PU.1. These results enlighten clinical translation research of PU.1 epigenetic regulation as a potential sepsis immune-checkpoint treatment site.

Estimating Need for Glasses and Hearing Aids in The Gambia: Results from a National Survey and Comparison of Clinical Impairment and Self-Report Assessment Approaches.

Few estimates are available of the need for assistive devices (ADs) in African settings. This study aimed to estimate population-level need for glasses and hearing aids in The Gambia based on (1) clinical impairment assessment, and (2) self-reported AD awareness, and explore the relationship between the two methods. The Gambia 2019 National Eye Health Survey is a nationally representative population-based sample of 9188 adults aged 35+ years. Participants underwent standardised clinical vision assessments including the need for glasses (distance and near). Approximately 25% of the sample underwent clinical assessment of hearing and hearing aid need. Data were also collected on self-reported awareness, need and access barriers to vision and hearing ADs. Overall, 5.6% of the study population needed distance glasses (95% CI 5.0-6.3), 45.9% (95% CI 44.2-47.5) needed near glasses and 25.5% (95% CI 22.2-29.2) needed hearing aids. Coverage for each AD was very low (<4%). The agreement between self-report and clinical impairment assessment for AD need was poor. In conclusion, there is high prevalence and very low coverage for distance glasses, near glasses and hearing aids in The Gambia. Self-report measures alone will not provide an accurate estimate of AD need.

Long Non-Coding RNA Hotairm1 Promotes S100A9 Support of MDSC Expansion during Sepsis.

Myeloid-derived suppressor cells (MDSCs) expand during mouse and human sepsis, but the mechanism responsible for this is unclear. We previously reported that nuclear transport of S100A9 protein programs Gr1+CD11b+ myeloid precursors into MDSCs in septic mice. Here, we show that long non-coding RNA Hotairm1 converts MDSCs from an activator to a repressor state. Mechanistically, increased Hotairm1 expression in MDSCs in mice converted S100A9 from a secreted proinflammatory mediator to an immune repressor by binding to and shuttling it from cytosol to nucleus during late sepsis. High Hotairm1 levels were detected in exosomes shed from MDSCs from late septic mice. These exosomes inhibited lipopolysaccharide-stimulated secretion of S100A9 from early sepsis Gr1+CD11b+ cells. Importantly, Hotairm1 knockdown in late sepsis Gr1+CD11b+ MDSCs prevented S100A9 cytosol to nuclear transfer and decreased repression of proimmune T cells. Notably, ectopic expression of Hotairm1 in early sepsis Gr1+CD11b+ cells shuttled S100A9 to the nucleus and promoted the MDSC repressor phenotype. In support of translating the mechanistic concept to human sepsis, we found that Hotairm1 binds S100A9 protein in CD33+CD11b+HLA-DR- MDSCs during established sepsis. Together, these data support that Hotairm1 is a plausible molecular target for treating late sepsis immune suppression in humans and its immune repressor mechanism may be cell autonomous.

HuR promotes miRNA-mediated upregulation of NFI-A protein expression in MDSCs during murine sepsis.

Myeloid-derived suppressor cells (MDSCs) contribute to high mortality rates during sepsis, but how sepsis induces MDSCs is unclear. Previously we reported that microRNA (miR)-21 and miR-181b reprogram MDSCs in septic mice by increasing levels of DNA binding transcription factor, nuclear factor 1 (NFI-A). Here, we provide evidence that miR-21 and miR-181b stabilize NFI-A mRNA and increase NFI-A protein levels by recruiting RNA-binding proteins HuR and Ago1 to its 3' untranslated region (3'UTR). We also find that the NFI-A GU-rich element (GRE)-binding protein CUGBP1 counters miR-21 and miR-181b dependent NFI-A mRNA stabilization and decreases protein production by replacing 3'UTR bound Ago1 with Ago2. We confirmed the miR-21 and miR-181b dependent reprogramming pathway in MDSCs transfected with a luciferase reporter construct containing an NFI-A 3'UTR fragment with point mutations in the miRNA binding sites. These results suggest that targeting NFI-A in MDSCs during sepsis may enhance resistance to uncontrolled infection.

S100A9 maintains myeloid-derived suppressor cells in chronic sepsis by inducing miR-21 and miR-181b.

Myeloid-derived suppressor cells (MDSC) expand during sepsis, suppress both innate and adaptive immunity, and promote chronic immunosuppression, which characterizes the late/chronic phase of sepsis. We previously reported that the transcription factors Stat3 and C/EBPß synergize to induces the expression of microRNA (miR)-21 and miR-181b to promote MDSC expansion in a mouse model of polymicrobial sepsis that progresses from an early/acute proinflammatory phase to a late/chronic immunosuppressive stage. We also showed that Gr1+CD11b+ cells, the precursors of MDSCs, from mice genetically deficient in the inflammatory protein S100A9 lack miR-21 or miR-181b in late sepsis, and are not immunosuppressive. In the present study, we show that S100A9 induces miR-21 and miR-181b during the late sepsis phase. We find that S100A9 associates with and stabilizes the Stat3-C/EBPß protein complex that activates the miRNA promoters. Reconstituting Gr1+CD11b+ cells from S100A9 knockout mice with late sepsis with S100A9 protein restores the Stat3-C/EBPß protein complex and miRNA expressions, and switches the Gr1+CD11b+ cells into the immunosuppressive, MDSC phenotype. Importantly, we find that this process requires IL-10 mediated signaling, which induces S100A9 translocation from the cytosol to the nucleus. These results demonstrate that S100A9 promotes MDSC expansion and immunosuppression in late/chronic sepsis by inducing the expression of miR-21 and miR-181b.

IL-10 induces an immune repressor pathway in sepsis by promoting S100A9 nuclear localization and MDSC development.

The myeloid-related protein S100A9 reprograms Gr1+CD11b+ myeloid precursors into myeloid-derived suppressor cells (MDSCs) during murine sepsis. Here, we show that the immunosuppressive cytokine IL-10 supports S100A9 expression and its nuclear localization in MDSCs to function as immune repressors. To support this new concept, we showed that antibody mediated IL-10 blockade in wild-type mice after sepsis induction inhibited MDSC expansion during late sepsis, and that ectopic expression of S100A9 in Gr1+CD11b+ cells from S100A9 knockout mice switched them into the MDSC phenotype only in the presence of IL-10. Knockdown of S100A9 in MDSCs from wild-type mice with late sepsis confirmed our findings in the S100A9 knockout mice. We also found that while both IL-6 and IL-10 can activate S100A9 expression in naive Gr1+CD11b+ cells, only IL-10 can induce S100A9 nuclear localization. These results support that IL-10 drives the molecular path that generates MDSCs and enhances immunosuppression during late sepsis, and inform that targeting this immune repressor path may improve sepsis survival in mice.