OMIP-086: Full spectrum flow cytometry for high-dimensional immunophenotyping of mouse innate lymphoid cells

This 25-parameter, 22-color full spectrum flow cytometry panel was designed and optimized for the comprehensive enumeration and functional characterization of innate lymphoid cell (ILC) subsets in mouse tissues. The panel presented here allows the discrimination of ILC progenitors (ILCP), ILC1, ILC2, NCR+ ILC3, NCR− ILC3, CCR6+ lymphoid tissue-inducer (LTi)-like ILC3 and mature natural killer (NK) cell populations. Further characterization of ILC and NK cell functional profiles in response to stimulation is provided by the inclusion of subset-specific cytokine markers, and proliferation markers. Development and optimization of this panel was performed on freshly isolated cells from adult BALB/c lungs and small intestine lamina propria, and ex vivo stimulation with phorbol 12-myrisate 13-acetate, ionomycin, and pro-ILC activating cytokines

Efficacy of PD-1 checkpoint inhibitor therapy in melanoma and beyond: are peripheral T cell phenotypes the key?

Immunotherapy treatment strategies have proven effective in a limited portion of patients, where identifying responders from non-responders to treatment remains a challenge. While some indications can be drawn from invasive biopsies, we need more accessible methods for predicting response and better correlates of response prior to starting therapy. Recent work has identified differences in immune composition at baseline in peripheral blood from melanoma patients responding to PD-1 blockade treatment. Through flow cytometric analysis of T cell receptors, phenotypical features of CD8+ and CD4+ T cells and Tregs could allow for the stratification of treatment response. Analysing T cells within peripheral blood could potentially allow for the stratification of PD-1 treatment response prior to therapy in different cancer settings

Transplacental innate immune training via maternal microbial exposure: role of XBP1-ERN1 axis in dendritic cell precursor programming

We recently reported that offspring of mice treated during pregnancy with the microbial-derived immunomodulator OM-85 manifest striking resistance to allergic airways inflammation, and localized the potential treatment target to fetal conventional dendritic cell (cDC) progenitors. Here, we profile maternal OM-85 treatment-associated transcriptomic signatures in fetal bone marrow, and identify a series of immunometabolic pathways which provide essential metabolites for accelerated myelopoiesis. Additionally, the cDC progenitor compartment displayed treatment-associated activation of the XBP1-ERN1 signalling axis which has been shown to be crucial for tissue survival of cDC, particularly within the lungs. Our forerunner studies indicate uniquely rapid turnover of airway mucosal cDCs at baseline, with further large-scale upregulation of population dynamics during aeroallergen and/or pathogen challenge. We suggest that enhanced capacity for XBP1-ERN1-dependent cDC survival within the airway mucosal tissue microenvironment may be a crucial element of OM-85-mediated transplacental innate immune training which results in postnatal resistance to airway inflammatory disease

Protection against severe infant lower respiratory tract infections by immune training: mechanistic studies

BACKGROUND: Results from recent clinical studies suggest potential efficacy of immune training (IT)-based approaches for protection against severe lower respiratory tract infections in infants, but underlying mechanisms are unclear. OBJECTIVE: We used systems-level analyses to elucidate IT mechanisms in infants in a clinical trial setting. METHODS: Pre- and posttreatment peripheral blood mononuclear cells from a placebo-controlled trial in which winter treatment with the IT agent OM85 reduced infant respiratory infection frequency and/or duration were stimulated for 24 hours with the virus/bacteria mimics polyinosinic:polycytidylic acid/lipopolysaccharide. Transcriptomic profiling via RNA sequencing, pathway and upstream regulator analyses, and systems-level gene coexpression network analyses were used sequentially to elucidate and compare responses in treatment and placebo groups. RESULTS: In contrast to subtle changes in antivirus-associated polyinosinic:polycytidylic acid response profiles, the bacterial lipopolysaccharide-triggered gene coexpression network responses exhibited OM85 treatment-associated upregulation of IFN signaling. This was accompanied by network rewiring resulting in increased coordination of TLR4 expression with IFN pathway-associated genes (especially master regulator IRF7); segregation of TNF and IFN-γ (which potentially synergize to exaggerate inflammatory sequelae) into separate expression modules; and reduced size/complexity of the main proinflammatory network module (containing, eg, IL-1,IL-6, and CCL3). Finally, we observed a reduced capacity for lipopolysaccharide-induced inflammatory cytokine (eg, IL-6 and TNF) production in the OM85 group. CONCLUSION: These changes are consistent with treatment-induced enhancement of bacterial pathogen detection/clearance capabilities concomitant with enhanced capacity to regulate ensuing inflammatory response intensity and duration. We posit that IT agents exemplified by OM85 potentially protect against severe lower respiratory tract infections in infants principally by effects on innate immune responses targeting the bacterial components of the mixed respiratory viral/bacterial infections that are characteristic of this age group