A multivariate modeling framework to quantify immune checkpoint context-dependent stimulation on T cells

Cells receive, and adjust to, various stimuli, which function as part of complex microenvironments forming their “context”. The possibility that a given context impacts the response to a given stimulus defines “context-dependency” and it explains large parts of the functional variability of physiopathological and pharmacological stimuli. Currently, there is no framework to analyze and quantify context-dependency over multiple contexts and cellular response outputs. We established an experimental system including a stimulus of interest, applied to an immune cell type in several contexts. We studied the function of OX40 ligand (OX40L) on T helper (Th) cell differentiation, in 4 molecular (Th0, Th1, Th2, and Th17) and 11 dendritic cell (DC) contexts (monocyte-derived DC and cDC2 conditions). We measured 17 Th output cytokines in 302 observations, and developed a statistical modeling strategy to quantify OX40L context-dependency. This revealed highly variable context-dependency, depending on the output cytokine and context type itself. Among molecular contexts, Th2 was the most influential on OX40L function. Among DC contexts, the DC type rather than the activating stimuli was dominant in controlling OX40L context-dependency. This work mathematically formalizes the complex determinants of OX40L functionality, and provides a unique framework to decipher and quantify the context-dependent variability of any biomolecule or drug function.

Anti-asthmatic effect of Ping-Chuan Formula in asthmatic mice, and its molecular mechanism of action

Purpose: To investigate the anti-asthmatic effect of Ping-Chuan Formula (PCF) in a mouse model, and the associated molecular mechanisms.Methods: Asthma mice were induced using ovalbumin (OVA), and PCF (600 mg/kg) was administered to the mice for 4 weeks. Sections of lung tissues were examined microscopically. The expressions of interleukins (ILs), interferon (IFN)-γ, transforming growth factor (TGF)-β were assayed, while lung tissue expressions of Toll like receptor (TLR)-4, GATA binding protein (GATA)-3, Ox40 ligand (OX40L), indoleamine 2,3-dioxygenase (IDO), and forkhead box P3 (Foxp3) determined. The T box expressed in T cells (T-bet) was evaluated using western blotting. The expressions of MHC II and co-stimulators (CD 11c, CD 80 and CD 86) of dendritic cells (DCs) were determined by flow cytometry.Results: PCF decreased inflammation in lung, and also down-regulated IL-4, -6, -17 and TGF-β (p < 0.01), whereas IL-10 and IFN-γ expressions were up-regulated (p < 0.01). Moreover, PCF decreased the expressions of TLR-4, GATA-3 and OX40L in lung tissue, and promoted Foxp3, IDO and T-bet. Besides, PCF decreased the levels of MHC II and co-stimulators (CD 80 and CD 86) on the surface of DCs.Conclusion: PCF exerts anti-asthmatic effect in mice via inhibition of inflammation, and modulation of MHC II and co-stimulators on the surface of DCs. These findings suggest that PCF is a promising candidate drug for treating asthma in humans.

SARS-CoV-2 induces human plasmacytoid predendritic cell diversification via UNC93B and IRAK4

Several studies have analyzed antiviral immune pathways in late-stage severe COVID-19. However, the initial steps of SARS-CoV-2 antiviral immunity are poorly understood. Here we have isolated primary SARS-CoV-2 viral strains and studied their interaction with human plasmacytoid predendritic cells (pDCs), a key player in antiviral immunity. We show that pDCs are not productively infected by SARS-CoV-2. However, they efficiently diversified into activated P1-, P2-, and P3-pDC effector subsets in response to viral stimulation. They expressed CD80, CD86, CCR7, and OX40 ligand at levels similar to influenza virus–induced activation. They rapidly produced high levels of interferon-α, interferon-λ1, IL-6, IP-10, and IL-8. All major aspects of SARS-CoV-2–induced pDC activation were inhibited by hydroxychloroquine. Mechanistically, SARS-CoV-2–induced pDC activation critically depended on IRAK4 and UNC93B1, as established using pDC from genetically deficient patients. Overall, our data indicate that human pDC are efficiently activated by SARS-CoV-2 particles and may thus contribute to type I IFN–dependent immunity against SARS-CoV-2 infection.

Extracellular vesicles produced by immunomodulatory cells harboring OX40 ligand and 4-1BB ligand enhance antitumor immunity

Genetically modified tumor cells harboring immunomodulators may be used as therapeutic vaccines to stimulate antitumor immunity. The therapeutic benefit of these tumor vaccines is extensively investigated and mechanisms by which they boost antitumor response may be further explored. Tumor cells are large secretors of extracellular vesicles (EVs). These EVs are able to vehiculate RNA and proteins to target cells, and engineered EVs also vehiculate recombinant proteins. In this study, we explore immunomodulatory properties of EVs derived from antitumor vaccines expressing the TNFSF ligands 4-1BBL and OX40L, modulating immune response mediated by immune cells and eliminating tumors. Our results suggest that the EVs secreted by genetically modified tumor cells harboring TNFSF ligands can induce T cell proliferation, inhibit the transcription factor FoxP3, associated with the maintenance of Treg phenotype, and enhance antitumor activity mediated by immune cells. The immunomodulatory extracellular vesicles have potential to be further engineered for developing new approaches for cancer therapy.

Immunomodulatory drugs suppress Th1-inducing ability of dendritic cells but enhance Th2-mediated allergic responses

Immunomodulatory drugs (IMiDs), lenalidomide and pomalidomide, are widely used treatments for multiple myeloma; however, they occasionally lead to episodes of itchy skin and rashes. Here, we analyzed the effects of IMiDs on human myeloid dendritic cells (mDCs) as major regulators of Th1 or Th2 responses and the role they play in allergy. We found that lenalidomide and pomalidomide used at clinical concentrations did not affect the survival or CD86 and OX40-ligand expression of blood mDCs in response to lipopolysaccharide (LPS) and thymic stromal lymphopoietin (TSLP) stimulation. Both lenalidomide and pomalidomide dose-dependently inhibited interleukin-12 (IL-12) and TNF production and STAT4 expression, and enhanced IL-10 production in response to LPS. When stimulated with TSLP, both IMiDs significantly enhanced CCL17 production and STAT6 and IRF4 expression and promoted memory Th2-cell responses. In 46 myeloma patients, serum CCL17 levels at the onset of lenalidomide-associated rash were significantly higher than those without rashes during lenalidomide treatment and those before treatment. Furthermore, serum CCL17 levels in patients who achieved a very good partial response (VGPR) were significantly higher compared with a less than VGPR during lenalidomide treatment. The median time to next treatment was significantly longer in lenalidomide-treated patients with rashes than those without. Collectively, IMiDs suppressed the Th1-inducing capacity of DCs, instead promoting a Th2 response. Thus, the lenalidomide-associated rashes might be a result of an allergic response driven by Th2-axis activation. Our findings suggest clinical efficacy and rashes as a side effect of IMiDs are inextricably linked through immunostimulation.