Longitudinal effects of elexacaftor/tezacaftor/ivacaftor on sputum viscoelastic properties, airway infection and inflammation in patients with cystic fibrosis.

BACKGROUND: Recent studies demonstrated that the triple combination cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI) improves lung function and reduces pulmonary exacerbations in cystic fibrosis (CF) patients with at least one F508del allele. However, effects of ETI on downstream consequences of CFTR dysfunction, i.e. abnormal viscoelastic properties of airway mucus, chronic airway infection and inflammation have not been studied. The aim of this study was to determine the longitudinal effects of ETI on airway mucus rheology, microbiome and inflammation in CF patients with one or two F508del alleles aged ≥12 years throughout the first 12 months of therapy. METHODS: In this prospective observational study, we assessed sputum rheology, the microbiome, inflammation markers and proteome before and 1, 3 and 12 months after initiation of ETI. RESULTS: In total, 79 patients with CF and at least one F508del allele and 10 healthy controls were enrolled in this study. ETI improved the elastic modulus and viscous modulus of CF sputum at 3 and 12 months after initiation (all p<0.01). Furthermore, ETI decreased the relative abundance of Pseudomonas aeruginosa in CF sputum at 3 months and increased the microbiome α-diversity at all time points. In addition, ETI reduced interleukin-8 at 3 months (p<0.05) and free neutrophil elastase activity at all time points (all p<0.001), and shifted the CF sputum proteome towards healthy. CONCLUSIONS: Our data demonstrate that restoration of CFTR function by ETI improves sputum viscoelastic properties, chronic airway infection and inflammation in CF patients with at least one F508del allele over the first 12 months of therapy; however, levels close to healthy were not reached.

Phage capsid nanoparticles with defined ligand arrangement block influenza virus entry.

Multivalent interactions at biological interfaces occur frequently in nature and mediate recognition and interactions in essential physiological processes such as cell-to-cell adhesion. Multivalency is also a key principle that allows tight binding between pathogens and host cells during the initial stages of infection. One promising approach to prevent infection is the design of synthetic or semisynthetic multivalent binders that interfere with pathogen adhesion1-4. Here, we present a multivalent binder that is based on a spatially defined arrangement of ligands for the viral spike protein haemagglutinin of the influenza A virus. Complementary experimental and theoretical approaches demonstrate that bacteriophage capsids, which carry host cell haemagglutinin ligands in an arrangement matching the geometry of binding sites of the spike protein, can bind to viruses in a defined multivalent mode. These capsids cover the entire virus envelope, thus preventing its binding to the host cell as visualized by cryo-electron tomography. As a consequence, virus infection can be inhibited in vitro, ex vivo and in vivo. Such highly functionalized capsids present an alternative to strategies that target virus entry by spike-inhibiting antibodies5 and peptides6 or that address late steps of the viral replication cycle7.

Single-cell transcriptomes of murine bone marrow stromal cells reveal niche-associated heterogeneity.

Bone marrow (BM) stromal cells are important in the development and maintenance of cells of the immune system. Using single cell RNA sequencing, we here explore the functional and phenotypic heterogeneity of individual transcriptomes of 1167 murine BM mesenchymal stromal cells. These cells exhibit a tremendous heterogeneity of gene expression, which precludes the identification of defined subpopulations. However, according to the expression of 108 genes involved in the communication of stromal cells with hematopoietic cells, we have identified 14 non-overlapping subpopulations, with distinct cytokine or chemokine gene expression signatures. With respect to the maintenance of subsets of immune memory cells by stromal cells, we identified distinct subpopulations expressing Il7, Il15 and Tnfsf13b. Together, this study provides a comprehensive dissection of the BM stromal heterogeneity at the single cell transcriptome level and provides a basis to understand their lifestyle and their role as organizers of niches for the long-term maintenance of immune cells.

MicroRNA-31 Reduces the Motility of Proinflammatory T Helper 1 Lymphocytes.

Proinflammatory type 1 T helper (Th1) cells are enriched in inflamed tissues and contribute to the maintenance of chronic inflammation in rheumatic diseases. Here we show that the microRNA- (miR-) 31 is upregulated in murine Th1 cells with a history of repeated reactivation and in memory Th cells isolated from the synovial fluid of patients with rheumatic joint disease. Knock-down of miR-31 resulted in the upregulation of genes associated with cytoskeletal rearrangement and motility and induced the expression of target genes involved in T cell activation, chemokine receptor- and integrin-signaling. Accordingly, inhibition of miR-31 resulted in increased migratory activity of repeatedly activated Th1 cells. The transcription factors T-bet and FOXO1 act as positive and negative regulators of T cell receptor (TCR)-mediated miR-31 expression, respectively. Taken together, our data show that a gene regulatory network involving miR-31, T-bet, and FOXO1 controls the migratory behavior of proinflammatory Th1 cells.

Nonfollicular reactivation of bone marrow resident memory CD4 T cells in immune clusters of the bone marrow.

The bone marrow maintains memory CD4 T cells, which provide memory to systemic antigens. Here we demonstrate that memory CD4 T cells are reactivated by antigen in the bone marrow. In a secondary immune response, antigen-specific T cells of the bone marrow mobilize and aggregate in immune clusters together with MHC class II-expressing cells, mostly B lymphocytes. They proliferate vigorously and express effector cytokines, but they do not develop into follicular T-helper cells. Neither do the B lymphocytes develop into germinal center B cells in the bone marrow. Within 10 days, the immune clusters disappear again. Within 30 days, the expanded antigen-specific memory CD4 T cells return to memory niches and are maintained again individually as resting cells. Thus, in secondary immune responses in the bone marrow T-cell memory is amplified, while in germinal center reactions of secondary lymphoid organs humoral memory is adapted by affinity maturation.

Selective targeting of pro-inflammatory Th1 cells by microRNA-148a-specific antagomirs in vivo.

In T lymphocytes, expression of miR-148a is induced by T-bet and Twist1, and is specific for pro-inflammatory Th1 cells. In these cells, miR-148a inhibits the expression of the pro-apoptotic protein Bim and promotes their survival. Here we use sequence-specific cholesterol-modified oligonucleotides against miR-148a (antagomir-148a) for the selective elimination of pro-inflammatory Th1 cells in vivo. In the murine model of transfer colitis, antagomir-148a treatment reduced the number of pro-inflammatory Th1 cells in the colon of colitic mice by 50% and inhibited miR-148a expression by 71% in the remaining Th1 cells. Expression of Bim protein in colonic Th1 cells was increased. Antagomir-148a-mediated reduction of Th1 cells resulted in a significant amelioration of colitis. The effect of antagomir-148a was selective for chronic inflammation. Antigen-specific memory Th cells that were generated by an acute immune reaction to nitrophenylacetyl-coupled chicken gamma globulin (NP-CGG) were not affected by treatment with antagomir-148a, both during the effector and the memory phase. In addition, antibody titers to NP-CGG were not altered. Thus, antagomir-148a might qualify as an effective drug to selectively deplete pro-inflammatory Th1 cells of chronic inflammation without affecting the protective immunological memory.

Linear polysialoside outperforms dendritic analogs for inhibition of influenza virus infection in vitro and in vivo.

Inhibition of influenza A virus infection by multivalent sialic acid inhibitors preventing viral hemagglutinin binding to host cells of the respiratory tract is a promising strategy. However, optimal geometry and optimal ligand presentation on multivalent scaffolds for efficient inhibition both in vitro and in vivo application are still unclear. Here, by comparing linear and dendritic polyglycerol sialosides (LPGSA and dPGSA) we identified architectural requirements and optimal ligand densities for an efficient multivalent inhibitor of influenza virus A/X31/1 (H3N2). Due to its large volume, the LPGSA at optimal ligand density sterically shielded the virus significantly better than the dendritic analog. A statistical mechanics model rationalizes the relevance of ligand density, morphology, and the size of multivalent scaffolds for the potential to inhibit virus-cell binding. Optimized LPGSA inhibited virus infection at IC50 in the low nanomolar nanoparticle concentration range and also showed potent antiviral activity against two avian influenza strains A/Mallard/439/2004 (H3N2) and A/turkey/Italy/472/1999 (H7N1) post infection. In vivo application of inhibitors clearly confirmed the higher inhibition potential of linear multivalent scaffolds to prevent infection. The optimized LPGSA did not show any acute toxicity, and was much more potent than the neuraminidase inhibitor oseltamivir carboxylate in vivo. Combined application of the LPGSA and oseltamivir carboxylate revealed a synergistic inhibitory effect and successfully prevented influenza virus infection in mice.

Multivalent Peptide-Nanoparticle Conjugates for Influenza-Virus Inhibition.

To inhibit binding of the influenza A virus to the host cell glycocalyx, we generate multivalent peptide-polymer nanoparticles binding with nanomolar affinity to the virus via its spike protein hemagglutinin. The chosen dendritic polyglycerol scaffolds are highly biocompatible and well suited for a multivalent presentation. We could demonstrate in vitro that by increasing the size of the polymer scaffold and adjusting the peptide density, viral infection is drastically reduced. Such a peptide-polymer conjugate qualified also in an in vivo infection scenario. With this study we introduce the first non-carbohydrate-based, covalently linked, multivalent virus inhibitor in the nano- to picomolar range by ensuring low peptide-ligand density on a larger dendritic scaffold.

Tracking CNS and systemic sources of oxidative stress during the course of chronic neuroinflammation.

The functional dynamics and cellular sources of oxidative stress are central to understanding MS pathogenesis but remain elusive, due to the lack of appropriate detection methods. Here we employ NAD(P)H fluorescence lifetime imaging to detect functional NADPH oxidases (NOX enzymes) in vivo to identify inflammatory monocytes, activated microglia, and astrocytes expressing NOX1 as major cellular sources of oxidative stress in the central nervous system of mice affected by experimental autoimmune encephalomyelitis (EAE). This directly affects neuronal function in vivo, indicated by sustained elevated neuronal calcium. The systemic involvement of oxidative stress is mirrored by overactivation of NOX enzymes in peripheral CD11b(+) cells in later phases of both MS and EAE. This effect is antagonized by systemic intake of the NOX inhibitor and anti-oxidant epigallocatechin-3-gallate. Together, this persistent hyper-activation of oxidative enzymes suggests an "oxidative stress memory" both in the periphery and CNS compartments, in chronic neuroinflammation.

miR-148a is upregulated by Twist1 and T-bet and promotes Th1-cell survival by regulating the proapoptotic gene Bim.

Repeatedly activated T helper 1 (Th1) cells present during chronic inflammation can efficiently adapt to the inflammatory milieu, for example, by expressing the transcription factor Twist1, which limits the immunopathology caused by Th1 cells. Here, we show that in repeatedly activated murine Th1 cells, Twist1 and T-bet induce expression of microRNA-148a (miR-148a). miR-148a regulates expression of the proapoptotic gene Bim, resulting in a decreased Bim/Bcl2 ratio. Inhibition of miR-148a by antagomirs in repeatedly activated Th1 cells increases the expression of Bim, leading to enhanced apoptosis. Knockdown of Bim expression by siRNA in miR-148a antagomir-treated cells restores viability of the Th1 cells, demonstrating that miR-148a controls survival by regulating Bim expression. Thus, Twist1 and T-bet not only control the differentiation and function of Th1 cells, but also their persistence in chronic inflammation.

Nuclear factor of activated T cells regulates the expression of interleukin-4 in Th2 cells in an all-or-none fashion.

Th2 memory lymphocytes have imprinted their Il4 genes epigenetically for expression in dependence of T cell receptor restimulation. However, in a given restimulation, not all Th cells with a memory for IL-4 expression express IL-4. Here, we show that in reactivated Th2 cells, the transcription factors NFATc2, NF-kB p65, c-Maf, p300, Brg1, STAT6, and GATA-3 assemble at the Il4 promoter in Th2 cells expressing IL-4 but not in Th2 cells not expressing it. NFATc2 is critical for assembly of this transcription factor complex. Because NFATc2 translocation into the nucleus occurs in an all-or-none fashion, dependent on complete dephosphorylation by calcineurin, NFATc2 controls the frequencies of cells reexpressing Il4, translates analog differences in T cell receptor stimulation into a digital decision for Il4 reexpression, and instructs all reexpressing cells to express the same amount of IL-4. This analog-to-digital conversion may be critical for the immune system to respond to low concentrations of antigens.