Publications by Year: 2021

2021
Marchetti L, Francisco D, Soldati S, Jahromi N, Barcos S, Gruber I, Pareja J, Thiriot A, von Andrian U, Deutsch U, et al. ACKR1 favors transcellular over paracellular T-cell diapedesis across the blood-brain barrier in neuroinflammation in vitro. European Journal of Immunology. 2021.Abstract
The migration of CD4+ effector/memory T cells across the blood-brain barrier (BBB) is a critical step in MS or its animal model, EAE. T-cell diapedesis across the BBB can occur paracellular, via the complex BBB tight junctions or transcellular via a pore through the brain endothelial cell body. Making use of primary mouse brain microvascular endothelial cells (pMBMECs) as in vitro model of the BBB, we here directly compared the transcriptome profile of pMBMECs favoring transcellular or paracellular T-cell diapedesis by RNA sequencing (RNA-seq). We identified the atypical chemokine receptor 1 (Ackr1) as one of the main candidate genes upregulated in pMBMECs favoring transcellular T-cell diapedesis. We confirmed upregulation of ACKR1 protein in pMBMECs promoting transcellular T-cell diapedesis and in venular endothelial cells in the CNS during EAE. Lack of endothelial ACKR1 reduced transcellular T-cell diapedesis across pMBMECs under physiological flow in vitro. Combining our previous observation that endothelial ACKR1 contributes to EAE pathogenesis by shuttling chemokines across the BBB, the present data support that ACKR1 mediated chemokine shuttling enhances transcellular T-cell diapedesis across the BBB during autoimmune neuroinflammation.
_ackr1_favors_transcellular_over_paracellular_t-cell_diapedesis_across_the_blood-brain_barrier_in_neuroinflammation_in_vitro.pdf
Mysore V, Cullere X, Mears J, Rosetti F, Okubo K, Liew PX, Zhang F, Madera-Salcedo I, Rosenbauer F, Stone RM, et al. FcγR engagement reprograms neutrophils into antigen cross-presenting cells that elicit acquired anti-tumor immunity. Nature Communications. 2021.Abstract
Classical dendritic cells (cDC) are professional antigen-presenting cells (APC) that regulate immunity and tolerance. Neutrophil-derived cells with properties of DCs (nAPC) are observed in human diseases and after culture of neutrophils with cytokines. Here we show that FcγR-mediated endocytosis of antibody-antigen complexes or an anti-FcγRIIIB-antigen conjugate converts neutrophils into nAPCs that, in contrast to those generated with cytokines alone, activate T cells to levels observed with cDCs and elicit CD8+ T cell-dependent anti-tumor immunity in mice. Single cell transcript analyses and validation studies implicate the transcription factor PU.1 in neutrophil to nAPC conversion. In humans, blood nAPC frequency in lupus patients correlates with disease. Moreover, anti-FcγRIIIB-antigen conjugate treatment induces nAPCs that can activate autologous T cells when using neutrophils from individuals with myeloid neoplasms that harbor neoantigens or those vaccinated against bacterial toxins. Thus, anti-FcγRIIIB-antigen conjugate-induced conversion of neutrophils to immunogenic nAPCs may represent a possible immunotherapy for cancer and infectious diseases.
fcgr_engagement_reprograms_neutrophils_into_antigen_cross-presenting_cells_that_elicit_acquired_anti-tumor_immunity_supplementary_data.pdf fcgr_engagement_reprograms_neutrophils_into_antigen_cross-presenting_cells_that_elicit_acquired_anti-tumor_immunity_paper.pdf
Vollmann EH, Rattay K, Barreiro O, Thiriot A, Fuhlbrigge RA, Vrbanac V, Kim K-W, Jung S, Tager AM, von Andrian UH. Specialized transendothelial dendritic cells mediate thymic T cell selection against blood-borne macromolecules. Nature Communications. 2021. Publisher's VersionAbstract
T cells undergo rigorous selection in the thymus to ensure self-tolerance and prevent autoimmunity, with this process requiring innocuous self-antigens (Ags) to be presented to thymocytes. Self-Ags are either expressed by thymic stroma cells or transported to the thymus from the periphery by migratory dendritic cells (DCs); meanwhile, small bloodborne peptides can access the thymic parenchyma by diffusing across the vascular lining. Here we describe an additional pathway of thymic Ag acquisition that enables circulating antigenic macromolecules to access both murine and human thymi. This pathway depends on a subset of thymus-resident DCs, distinct from both parenchymal and circulating migratory DCs, that are positioned in immediate proximity to thymic microvessels where they extend cellular processes across the endothelial barrier into the blood stream. Transendothelial positioning of DCs depends on DC-expressed CX3CR1 and its endothelial ligand, CX3CL1, and disrupting this chemokine pathway prevents thymic acquisition of circulating proteins and compromises negative selection of Ag-reactive thymocytes. Thus, transendothelial DCs represent a mechanism by which the thymus can actively acquire blood-borne Ags to induce and maintain central tolerance.
vollmann_et_al-2021-nature_communications.pdf 1.mp4 2.mp4 3.mp4 4.mp4 5.mp4 vollmann_et_al-2021-nature_communications.sup-1.pdf
Barkaway A, Rolas L, Joulia R, Bodkin J, Lenn T, Owen-Woods C, Reglero-Real N, Stein M, Vázquez-Martínez L, Girbl T, et al. Age-related changes in the local milieu of inflamed tissues cause aberrant neutrophil trafficking and subsequent remote organ damage. Immunity. 2021. Publisher's VersionAbstract

Aging is associated with dysregulated immune functions. Here, we investigated the impact of age on neutrophil diapedesis. Using confocal intravital microscopy, we found that in aged mice, neutrophils adhered to vascular endothelium in inflamed tissues but exhibited a high frequency of reverse transendothelial migration (rTEM). This retrograde breaching of the endothelium by neutrophils was governed by enhanced production of the chemokine CXCL1 from mast cells that localized at endothelial cell (EC) junctions. Increased EC expression of the atypical chemokine receptor 1 (ACKR1) supported this pro-inflammatory milieu in aged venules. Accumulation of CXCL1 caused desensitization of the chemokine receptor CXCR2 on neutrophils and loss of neutrophil directional motility within EC junctions. Fluorescent tracking revealed that in aged mice, neutrophils undergoing rTEM re-entered the circulation and disseminated to the lungs where they caused vascular leakage. Thus, neutrophils stemming from a local inflammatory site contribute to remote organ damage, with implication to the dysregulated systemic inflammation associated with aging.

Keywords: ACKR1; CXCR2; Neutrophils; aging; chemokines; diapedesis; endothelium; extravasation; inflammation; mast cells.

age-related_changes_in_the_local_milieu_of_inflamed_tissues_cause_aberrant_neutrophil_trafficking_and_subsequent_remote_organ_damage_paper_and_supp_materials.pdf
Stutte S, Ruf J, Kugler I, Ishikawa-Ankerhold H, Parzefall A, Marconi P, Maeda T, Kaisho T, Krug A, Popper B, et al. Type I interferon mediated induction of somatostatin leads to suppression of ghrelin and appetite thereby promoting viral immunity in mice. Brain Behavior and Immunity. 2021. Publisher's VersionAbstract
Loss of appetite (anorexia) is a typical behavioral response to infectious diseases that often reduces body weight. Also, anorexia can be observed in cancer and trauma patients, causing poor quality of life and reduced prospects of positive therapeutic outcomes. Although anorexia is an acute symptom, its initiation and endocrine regulation during antiviral immune responses are poorly understood. During viral infections, plasmacytoid dendritic cells (pDCs) produce abundant type I interferon (IFN-I) to initiate first-line defense mechanisms. Here, by targeted ablation of pDCs and various in vitro and in vivo mouse models of viral infection and inflammation, we identified that IFN-I is a significant driver of somatostatin (SST). Consequently, SST suppressed the hunger hormone ghrelin that led to severe metabolic changes, anorexia, and rapid body weight loss. Furthermore, during vaccination with Modified Vaccinia Ankara virus (MVA), the SST-mediated suppression of ghrelin was critical to viral immune response, as ghrelin restrained the production of early cytokines by natural killer (NK) cells and pDCs, and impaired the clonal expansion of CD8+ T cells. Thus, the hormonal modulation of ghrelin through SST and the cytokine IFN-I is fundamental for optimal antiviral immunity, which comes at the expense of calorie intake.
Type I interferon mediated induction of somatostatin leads to suppression of ghrelin and appetite thereby promoting viral immunity in mice.pdf Type I interferon mediated induction of somatostatin leads to suppression of ghrelin and appetite thereby promoting viral immunity in mice_Supplementary_Materials.zip
Kochappan R, Cao E, Han S, Hu L, Quach T, Senyschyn D, Ferreira VI, Lee G, Leong N, Sharma G, et al. Targeted delivery of mycophenolic acid to the mesenteric lymph node using a triglyceride mimetic prodrug approach enhances gut-specific immunomodulation in mice. Journal of Controlled Release. 2021;(332) :636-651. Publisher's VersionAbstract
The mesenteric lymph nodes (MLN) are a key site for the generation of adaptive immune responses to gut-derived antigenic material and immune cells within the MLN contribute to the pathophysiology of a range of conditions including inflammatory and autoimmune diseases, viral infections, graft versus host disease and cancer. Tar-geting immunomodulating drugs to the MLN may thus be beneficial in a range of conditions. This paper in-vestigates the potential benefit of targeting a model immunosuppressant drug, mycophenolic acid (MPA), to T cells in the MLN, using a triglyceride (TG) mimetic prodrug approach. We confirmed that administration of MPA in the TG prodrug form (MPA-TG), increased lymphatic transport of MPA-related species 83-fold and increased MLN concentrations of MPA >20 fold, when compared to MPA alone, for up to 4 h in mice. At the same time, the plasma exposure of MPA and MPA-TG was similar, limiting the opportunity for systemic side effects. Confocal microscopy and flow cytometry studies with a fluorescent model prodrug (Bodipy-TG) revealed that the prodrug accumulated in the MLN cortex and paracortex at 5 and 10 h following administration and was highly associated with B cells and T cells that are found in these regions of the MLN. Finally, we demonstrated that MPA-TG was significantly more effective than MPA at inhibiting CD4+and CD8+T cell proliferation in the MLN of mice in response to  an  oral ovalbumin antigen challenge. In  contrast, MPA-TG was no  more effective than MPA at inhibiting T cell proliferation in peripheral LN when mice were challenged via SC administration of ovalbumin. This paper provides the first evidence of an in vivo pharmacodynamic benefit of targeting the MLN using a TG mimetic prodrug approach. The TG mimetic prodrug technology has the potential to benefit the treatment of a range of conditions where aberrant immune responses are initiated in gut-associated lymphoid tissues.
Targeted delivery of mycophenolic acid to the mesenteric lymph node using a triglyceride mimetic prodrug approach enhances gut-specific immunomodulation in mice.pdf Targeted delivery of mycophenolic acid to the mesenteric lymph node using a triglyceride mimetic prodrug approach enhances gut-specific immunomodulation in mice_Supplementary_Material..docx
von Andrian UH. NK cell memory: discovery of a mystery. Nature Immunology. 2021.Abstract
Ulrich von Andrian recounts how an unexpected experimental result called into question a well-established concept in immunology: the mechanism of immune memory. Follow-up experiments revealed that NK cells can mediate antigen-specific adaptive immune responses.
nk_cell_memory-_discovery_of_a_mystery.pdf
Huang S, Ziegler C, Austin J, Mannoun N, Vukovic M, Ordovas-Montanes J, Shalek A, von Andrian UH. Lymph nodes are innervated by a unique population of sensory neurons with immunomodulatory potential. Cell. 2021;184 (2) :441-459. Publisher's VersionAbstract
Immune responses within barrier tissues are regulated, in part, by nociceptors, specialized peripheral sensory neurons that detect noxious stimuli. Previous work has shown that nociceptor ablation not only alters local responses to immune challenge at peripheral sites, but also within draining lymph nodes (LNs). The mechanisms and significance of nociceptor-dependent modulation of LN function are unknown. Indeed, although sympathetic innervation of LNs is well documented, it has been unclear whether the LN parenchyma itself is innervated by sensory neurons. Here, using a combination of high-resolution imaging, retrograde viral tracing, single-cell transcriptomics (scRNA-seq), and optogenetics, we identified and functionally tested a sensory neuro-immune circuit that is preferentially located in the outermost cortex of skin-draining LNs. Transcriptomic profiling revealed that there are at least four discrete subsets of sensory neurons that innervate LNs with a predominance of peptidergic nociceptors, and an innervation pattern that is distinct from that in the surrounding skin. To uncover potential LN-resident communication partners for LN-innervating sensory neurons, we employed scRNA-seq to generate a draft atlas of all murine LN cells and, based on receptor-ligand expression patterns, nominated candidate target populations among stromal and immune cells. Using selective optogenetic stimulation of LN-innervating sensory axons, we directly experimentally tested our inferred connections. Acute neuronal activation triggered rapid transcriptional changes preferentially within our top-ranked putative interacting partners, principally endothelium and other nodal stroma cells, as well as several innate leukocyte populations. Thus, LNs are monitored by a unique population of sensory neurons that possesses immunomodulatory potential.
Lymph nodes are innervated by a unique population of sensory neurons with immunomodulatory potential.pdf Lymph nodes are innervated by a unique population of sensory neurons with immunomodulatory potential_Supplementary_Materials.zip