Giuseppe Penna

@humanitas.net

Humanitas research Hospital

89

Scopus Publications

Scopus Publications

  • Prenatal antibiotics reduce breast milk IgA and induce dysbiosis in mouse offspring, increasing neonatal susceptibility to bacterial sepsis
    Carlo Pietrasanta, Carolina Carlosama, Michela Lizier, Giulia Fornasa, Tanja Rezzonico Jost, Sara Carloni, Silvia Giugliano, Alessandra Silvestri, Paola Brescia, Benedetta De Ponte Conti,et al.

    Elsevier BV


  • Optimizing abemaciclib-induced diarrhea management in patients with breast cancer: A pragmatic 2-group study using a postbiotic microbiota stabilizer
    Rita De Sanctis, Paola Tiberio, Flavia Jacobs, Mariangela Gaudio, Chiara Benvenuti, Laura Giordano, Rosalba Torrisi, Alberto Zambelli, Chiara Pozzi, Giuseppe Penna,et al.

    Oxford University Press (OUP)
    Abstract Background Abemaciclib-induced diarrhea is a relevant concern in clinical practice. Postbiotics have emerged as a promising option for managing it. Materials and Methods We conducted a retrospective-prospective, 2-group, observational study to assess the impact of the postbiotic PostbiotiX-Restore, derived by Lactobacillus paracasei CNCM I-5220, on abemaciclib-induced diarrhea in patients with hormone receptor-positive HER2-negative breast cancer. The prospective population (Postbio group) received postbiotic during the first cycle of abemaciclib, while the retrospective one received standard care (Standard group). Diarrhea grading was defined according to the National Cancer Institute’s Common Terminology Criteria for Adverse Events. Results During the first cycle, diarrhea occurred in 78.9% of patients in the Standard cohort and 97.1% in the Postbio one, with most cases being G1-G2. Severe (G3) diarrhea was significantly less frequent in the Postbio group (0%) compared to the Standard one (7.9%; P = .029). Over the entire study period, while the grading difference was not statistically significant, G3 events were less frequent in the Postbio population (5.9%) than the Standard one (15.4%). Moreover, Postbio patients required fewer dose reductions due to diarrhea compared to the Standard group (P = .002). Notably, in the Postbio population, G1 and G2 events had short median durations (3 and 1 days, respectively) and, for the 2 patients experiencing G3 events during the second abemaciclib cycle (off postbiotic), diarrhea lasted only 1 day. Conclusions Our study demonstrates the effect of PostbiotiX-Restore in mitigating abemaciclib-induced diarrhea, resulting in reduced severity, fewer dose reductions, and shorter duration. Further exploration and validation in larger cohorts are needed.


  • Porphyromonas gingivalis fuels colorectal cancer through CHI3L1-mediated iNKT cell-driven immune evasion
    Angélica Díaz-Basabe, Georgia Lattanzi, Federica Perillo, Chiara Amoroso, Alberto Baeri, Andrea Farini, Yvan Torrente, Giuseppe Penna, Maria Rescigno, Michele Ghidini,et al.

    Informa UK Limited
    The interaction between the gut microbiota and invariant Natural Killer T (iNKT) cells plays a pivotal role in colorectal cancer (CRC). Porphyromonas gingivalis is a keystone oral pathogen associated with CRC. The oral pathobiont Fusobacterium nucleatum influences the anti-tumour functions of CRC-infiltrating iNKT cells. However, the impact of other oral bacteria, like P. gingivalis, on their activation status remains unexplored. In this study, we demonstrate that mucosa-associated P. gingivalis induces a protumour phenotype in iNKT cells, subsequently influencing the composition of mononuclear-phagocyte cells within the tumour microenvironment in CRC. Mechanistically, in vivo and in vitro experiments show that P. gingivalis reduces the cytotoxic functions of iNKT cells, hampering the iNKT cell lytic machinery though increased expression of chitinase 3-like-1 protein (CHI3L1). Neutralization of CHI3L1 effectively restores iNKT cell cytotoxic functions suggesting a therapeutic potential to reactivate iNKT cell-mediated antitumour immunity. In conclusion, our data demonstrate how P. gingivalis accelerates CRC progression by inducing iNKT cells to upregulate CHI3L1, thus impairing iNKT cell cytotoxicity and promoting host tumour immune evasion.

  • Biomimetic superabsorbent hydrogel acts as a gut protective dynamic exoskeleton improving metabolic parameters and expanding A. muciniphila
    Alessandra Silvestri, Antonio Gil-Gomez, Milena Vitale, Daniele Braga, Christian Demitri, Paola Brescia, Marta Madaghiele, Ilaria Spadoni, Bryan Jones, Giulia Fornasa,et al.

    Elsevier BV

  • Sensitizing cancer cells to immune checkpoint inhibitors by microbiota-mediated upregulation of HLA class I
    Valentina Ferrari, Antonino Lo Cascio, Alessia Melacarne, Nina Tanasković, Alessandro M. Mozzarelli, Luca Tiraboschi, Michela Lizier, Marta Salvi, Daniele Braga, Francesca Algieri,et al.

    Elsevier BV

  • Can somatotype influence the static postural control? A new proposal of investigation
    Giuseppe Penna, Giulio Zecca, Gaetano Altavilla, Tiziana D'Isanto, and Luca Russo

    Asociacion Espanola de Analisis del Rendimiento Deportivo

  • Lactobacillus paracasei CNCM I-5220-derived postbiotic protects from the leaky-gut
    Francesca Algieri, Nina Tanaskovic, Cindy Cardenas Rincon, Elisabetta Notario, Daniele Braga, Graziano Pesole, Roberto Rusconi, Giuseppe Penna, and Maria Rescigno

    Frontiers Media SA
    The maintenance of intestinal barrier function is essential for preventing different pathologies, such as the leaky gut syndrome (LGS), which is characterized by the passage of harmful agents, like bacteria, toxins, and viruses, into the bloodstream. Intestinal barrier integrity is controlled by several players, including the gut microbiota. Various molecules, called postbiotics, are released during the natural metabolic activity of the microbiota. Postbiotics can regulate host–microbe interactions, epithelial homeostasis, and have overall benefits for our health. In this work, we used in vitro and in vivo systems to demonstrate the role of Lactobacillus paracasei CNCM I-5220-derived postbiotic (LP-PBF) in preserving intestinal barrier integrity. We demonstrated in vitro that LP-PBF restored the morphology of tight junctions (TJs) that were altered upon Salmonella typhimurium exposure. In vivo, LP-PBF protected the gut vascular barrier and blocked S. typhimurium dissemination into the bloodstream. Interestingly, we found that LP-PBF interacts not only with the host cells, but also directly with S. typhimurium blocking its biofilm formation, partially due to the presence of biosurfactants. This study highlights that LP-PBF is beneficial in maintaining gut homeostasis due to the synergistic effect of its different components. These results suggest that LP-PBF could be utilized in managing several pathologies displaying an impaired intestinal barrier function.

  • A ‘Multiomic’ Approach of Saliva Metabolomics, Microbiota, and Serum Biomarkers to Assess the Need of Hospitalization in Coronavirus Disease 2019
    Chiara Pozzi, Riccardo Levi, Daniele Braga, Francesco Carli, Abbass Darwich, Ilaria Spadoni, Bianca Oresta, Carola Conca Dioguardi, Clelia Peano, Leonardo Ubaldi,et al.

    Elsevier BV

  • Paralysis of the cytotoxic granule machinery is a new cancer immune evasion mechanism mediated by chitinase 3-like-1
    Abbass Darwich, Alessandra Silvestri, Mohamed-Reda Benmebarek, Juliette Mouriès, Bruno Cadilha, Alessia Melacarne, Lapo Morelli, Domenico Supino, Alexandre Taleb, Hannah Obeck,et al.

    BMJ
    BackgroundNatural killer (NK) cells require a functional lytic granule machinery to mediate effective antitumor responses. Evading the lytic cargo deployed at the immune synapse (IS) could be a critical step for cancer progression through yet unidentified mechanisms.MethodsNK cell antibody-dependent cellular cytotoxicity (ADCC) is a major determinant of the clinical efficacy of some therapeutic antibodies including the anti-HER2 Trastuzumab. Thus, we screened sera of Trastuzumab-resistant HER2 +patients with breast cancer for molecules that could inhibit NK cell ADCC. We validated our findings in vitro using cytotoxicity assays and confocal imaging of the lytic granule machinery and in vivo using syngeneic and xenograft murine models.ResultsWe found that sera from Trastuzumab-refractory patients could inhibit healthy NK cell ADCC in vitro. These sera contained high levels of the inflammatory protein chitinase 3-like 1 (CHI3L1) compared with sera from responders and healthy controls. We demonstrate that recombinant CHI3L1 inhibits both ADCC and innate NK cell cytotoxicity. Mechanistically, CHI3L1 prevents the correct polarization of the microtubule-organizing center along with the lytic granules to the IS by hindering the receptor of advanced glycation end-products and its downstream JNK signaling. In vivo, CHI3L1 administration drastically impairs the control of NK cell-sensitive tumors, while CHI3L1 blockade synergizes with ADCC to cure mice with HER2 +xenografts.ConclusionOur work highlights a new paradigm of tumor immune escape mediated by CHI3L1 which acts on the cytotoxic machinery and prevents granule polarization. Targeting CHI3L1 could mitigate immune escape and potentiate antibody and cell-based immunotherapies.

  • Identification of a choroid plexus vascular barrier closing during intestinal inflammation
    Sara Carloni, Alice Bertocchi, Sara Mancinelli, Martina Bellini, Marco Erreni, Antonella Borreca, Daniele Braga, Silvia Giugliano, Alessandro M. Mozzarelli, Daria Manganaro,et al.

    American Association for the Advancement of Science (AAAS)
    Description Locking down access to the brain Inflammatory bowel disease is best known for intestinal symptoms but can also cause a variety of extraintestinal manifestations in other organs. It can also be associated with cognitive and psychiatric effects, including anxiety and depression. Using mouse models of intestinal inflammation, Carloni et al. uncovered a potential pathogenic link between these aspects of inflammatory bowel disease. The inflammatory process causes the gut vascular barrier to become more permeable, resulting in the spread of inflammation beyond the intestine, while the vascular barrier in the choroid plexus shuts down, helping protect the brain from inflammation but also potentially impairing communication between organs and impairing some brain functions. —YN Gut and choroid plexus vascular barriers form a gut-brain axis involved in the modulation of systemic inflammation. Up to 40% of patients with inflammatory bowel disease present with psychosocial disturbances. We previously identified a gut vascular barrier that controls the dissemination of bacteria from the intestine to the liver. Here, we describe a vascular barrier in the brain choroid plexus (PVB) that is modulated in response to intestinal inflammation through bacteria-derived lipopolysaccharide. The inflammatory response induces PVB closure after gut vascular barrier opening by the up-regulation of the wingless-type, catenin-beta 1 (Wnt/β-catenin) signaling pathway, rendering it inaccessible to large molecules. In a model of genetically driven closure of choroid plexus endothelial cells, we observed a deficit in short-term memory and anxiety-like behavior, suggesting that PVB closure may correlate with mental deficits. Inflammatory bowel disease–related mental symptoms may thus be the consequence of a deregulated gut–brain vascular axis.

  • Identification of a class of non-conventional ER-stress-response-derived immunogenic peptides
    Alessia Melacarne, Valentina Ferrari, Luca Tiraboschi, Michele Mishto, Juliane Liepe, Marina Aralla, Laura Marconato, Michela Lizier, Chiara Pozzi, Offer Zeira,et al.

    Elsevier BV
    Efforts to overcome resistance to immune checkpoint blockade therapy have focused on vaccination strategies using neoepitopes, although they cannot be applied on a large scale due to the "private" nature of cancer mutations. Here, we show that infection of tumor cells with Salmonella induces the opening of membrane hemichannels and the extracellular release of proteasome-generated peptides by the exacerbation of endoplasmic reticulum (ER) stress. Peptides released by cancer cells foster an antitumor response in vivo, both in mice bearing B16F10 melanomas and in dogs suffering from osteosarcoma. Mass spectrometry analysis on the supernatant of human melanoma cells revealed 12 peptides capable of priming healthy-donor CD8+ T cells that recognize and kill human melanoma cells in vitro and when xenotransplanted in vivo. Hence, we identified a class of shared tumor antigens that are generated in ER-stressed cells, such as tumor cells, that do not induce tolerance and are not presented by healthy cells.

  • Gut vascular barrier impairment leads to intestinal bacteria dissemination and colorectal cancer metastasis to liver
    Alice Bertocchi, Sara Carloni, Paola Simona Ravenda, Giovanni Bertalot, Ilaria Spadoni, Antonino Lo Cascio, Sara Gandini, Michela Lizier, Daniele Braga, Francesco Asnicar,et al.

    Elsevier BV
    Metastasis is facilitated by the formation of a "premetastatic niche," which is fostered by primary tumor-derived factors. Colorectal cancer (CRC) metastasizes mainly to the liver. We show that the premetastatic niche in the liver is induced by bacteria dissemination from primary CRC. We report that tumor-resident bacteria Escherichia coli disrupt the gut vascular barrier (GVB), an anatomical structure controlling bacterial dissemination along the gut-liver axis, depending on the virulence regulator VirF. Upon GVB impairment, bacteria disseminate to the liver, boost the formation of a premetastatic niche, and favor the recruitment of metastatic cells. In training and validation cohorts of CRC patients, we find that the increased levels of PV-1, a marker of impaired GVB, is associated with liver bacteria dissemination and metachronous distant metastases. Thus, PV-1 is a prognostic marker for CRC distant recurrence and vascular impairment, leading to liver metastases.

  • Functional characterization and immunomodulatory properties of Lactobacillus helveticus strains isolated from Italian hard cheeses
    Miriam Zago, Lucia Massimiliano, Barbara Bonvini, Giuseppe Penna, Giorgio Giraffa, and Maria Rescigno

    Public Library of Science (PLoS)
    Lactobacillus helveticus carries many properties such as the ability to survive gastrointestinal transit, modulate the host immune response, accumulate biopeptides in milk, and adhere to the epithelial cells that could contribute to improving host health. In this study, the applicability as functional cultures of four L. helveticus strains isolated from Italian hard cheeses was investigated. A preliminary strain characterization showed that the ability to produce folate was generally low while antioxidant, proteolytic, peptidase, and β-galactosidase activities resulted high, although very variable, between strains. When stimulated moDCs were incubated in the presence of live cells, a dose-dependent release of both the pro-inflammatory cytokine IL-12p70 and the anti-inflammatory cytokine IL-10, was shown for all the four strains. In the presence of cell-free culture supernatants (postbiotics), a dose-dependent, decrease of IL-12p70 and an increase of IL-10 was generally observed. The immunomodulatory effect took place also in Caciotta-like cheese made with strains SIM12 and SIS16 as bifunctional (i.e., immunomodulant and acidifying) starter cultures, thus confirming tests in culture media. Given that the growth of bacteria in the cheese was not necessary (they were killed by pasteurization), the results indicated that some constituents of non-viable bacteria had immunomodulatory properties. This study adds additional evidence for the positive role of L. helveticus on human health and suggests cheese as a suitable food for delivering candidate strains and modulating their anti-inflammatory properties.

  • Endogenous murine microbiota member Faecalibaculum rodentium and its human homologue protect from intestinal tumour growth
    Elena Zagato, Chiara Pozzi, Alice Bertocchi, Tiziana Schioppa, Fabiana Saccheri, Silvia Guglietta, Bruno Fosso, Laura Melocchi, Giulia Nizzoli, Jacopo Troisi,et al.

    Springer Science and Business Media LLC
    The microbiota has been shown to promote intestinal tumourigenesis, but a possible anti-tumourigenic effect has also been postulated. Here, we demonstrate that changes in the microbiota and mucus composition are concomitant with tumourigenesis. We identified two anti-tumourigenic strains of the microbiota—Faecalibaculum rodentium and its human homologue, Holdemanella biformis—that are strongly under-represented during tumourigenesis. Reconstitution of ApcMin/+ or azoxymethane- and dextran sulfate sodium-treated mice with an isolate of F. rodentium (F. PB1) or its metabolic products reduced tumour growth. Both F. PB1 and H. biformis produced short-chain fatty acids that contributed to control protein acetylation and tumour cell proliferation by inhibiting calcineurin and NFATc3 activation in mouse and human settings. We have thus identified endogenous anti-tumourigenic bacterial strains with strong diagnostic, therapeutic and translational potential. The murine gut commensal Faecalibaculum rodentium and its human homologue, Holdemanella biformis, are under-represented in tumour development and can reduce tumour progression via short-chain fatty acid production, providing insights into a protective microbial candidate.

  • Microbiota-driven gut vascular barrier disruption is a prerequisite for non-alcoholic steatohepatitis development
    Juliette Mouries, Paola Brescia, Alessandra Silvestri, Ilaria Spadoni, Marcel Sorribas, Reiner Wiest, Erika Mileti, Marianna Galbiati, Pietro Invernizzi, Luciano Adorini,et al.

    Elsevier BV
    Graphical abstract


  • Genomic diversity and immunomodulatory activity of Lactobacillus plantarum isolated from dairy products
    M. Zago, E. Scaltriti, B. Bonvini, M.E. Fornasari, G. Penna, L. Massimiliano, D. Carminati, M. Rescigno, and G. Giraffa

    Wageningen Academic Publishers
    In this study, we aimed to investigate some functional characteristics and the immunomodulatory properties of three strains of Lactobacillus plantarum of dairy origin which, in a previous screening, showed to be candidate probiotics. Genome sequencing and comparative genomics, which confirmed the presence of genes involved in folate and riboflavin production and in the immune response of dendritic cells (DCs), prompted us to investigate the ability of the three strains to accumulate the two vitamins and their immunomodulation properties. The ability of the three strains to release antioxidant components in milk was also investigated. Small amounts of folate and riboflavin were produced by the three strains, while they showed a good antioxidant capacity in milk with FRAP method. The immune response experiments well correlated with the presence of candidate genes influencing in DCs cytokine response to L. plantarum. Specifically, the amounts of secreted cytokins by DCs after stimulation with cells of Lp790, Lp813 and Lp998 resulted pro-inflammatory whereas stimulation with culture supernatants (postbiotics) inhibited the release of interleukin (IL)-12p70 and increased the release of the anti-inflammatory IL-10 cytokine. This study adds further evidence on the importance of L. plantarum in human health. Understanding how probiotics (or postbiotics) work in preclinical models can allow a rational choice of the different strains for clinical and/or commercial use.

  • The EGFR-specific antibody cetuximab combined with chemotherapy triggers immunogenic cell death
    Chiara Pozzi, Alessandro Cuomo, Ilaria Spadoni, Elena Magni, Alessio Silvola, Alexia Conte, Sara Sigismund, Paola Simona Ravenda, Tiziana Bonaldi, Maria Giulia Zampino,et al.

    Springer Science and Business Media LLC
    Cetuximab is a monoclonal antibody that is effective in the treatment of metastatic colorectal cancer (mCRC). Cetuximab blocks epidermal growth factor receptor (EGFR)-ligand interaction and inhibits downstream RAS–ERK activation. However, only some activating mutations in RAS affect cetuximab efficacy, and it is not clear what else mediates treatment success. Here we hypothesized that cetuximab induces immunogenic cell death (ICD) that activates a potent antitumor response. We found that cetuximab, in combination with chemotherapy, fostered ICD in CRC cells, which we measured via the endoplasmic reticulum (ER) stress response and an increase in phagocytosis by dendritic cells. ICD induction depended on the mutational status of the EGFR signaling pathway and on the inhibition of the splicing of X-box binding protein 1 (XBP1), an unfolded protein response (UPR) mediator. We confirmed the enhanced immunogenicity elicited by cetuximab in a mouse model of human EGFR-expressing CRC. Overall, we demonstrate a new, immune-related mechanism of action of cetuximab that may help to tailor personalized medicine.

  • Coagulation induced by C3aR-dependent NETosis drives protumorigenic neutrophils during small intestinal tumorigenesis
    Silvia Guglietta, Andrea Chiavelli, Elena Zagato, Carsten Krieg, Sara Gandini, Paola Simona Ravenda, Barbara Bazolli, Bao Lu, Giuseppe Penna, and Maria Rescigno

    Springer Science and Business Media LLC
    Excessive activation of blood coagulation and neutrophil accumulation have been described in several human cancers. However, whether hypercoagulation and neutrophilia are linked and involved in cancer development is currently unknown. Here we show that spontaneous intestinal tumorigenesis correlates with the accumulation of low-density neutrophils with a pro-tumorigenic N2 phenotype and unprompted neutrophil extracellular traps (NET) formation. We find that increased circulating lipopolysaccharide induces upregulation of complement C3a receptor on neutrophils and activation of the complement cascade. This leads to NETosis, induction of coagulation and N2 polarization, which prompts tumorigenesis, showing a novel link between coagulation, neutrophilia and complement activation. Finally, in a cohort of patients with small but not large intestinal cancer, we find a correlation between neutrophilia and hypercoagulation. This study provides a mechanistic explanation for the tumour-promoting effects of hypercoagulation, which could be used as a new biomarker or as a therapeutic target.

  • A gut-vascular barrier controls the systemic dissemination of bacteria
    Ilaria Spadoni, Elena Zagato, Alice Bertocchi, Roberta Paolinelli, Edina Hot, Antonio Di Sabatino, Flavio Caprioli, Luca Bottiglieri, Amanda Oldani, Giuseppe Viale,et al.

    American Association for the Advancement of Science (AAAS)
    A gut bacterial containment system Trillions of bacteria selectively inhabit our guts, but how do our bodies keep them contained? Spadoni et al. describe a “gut-vascular barrier” that prevents intestinal microbes from accessing the liver and the bloodstream in mice (see the Perspective by Bouziat and Jabri). Studies with human samples and in mice revealed that the cell biology of the gut-vascular barrier shares similarities with the blood-brain barrier of the central nervous system. Pathogenic bacteria such as Salmonella typhimurium could penetrate the gut-vascular barrier in mice, gaining access to the liver and bloodstream, in a manner dependent on the Salmonella pathogenicity island 2–type III secretion system. Science, this issue p. 830; see also p. 742 An endothelial barrier between the gut and the bloodstream helps keep intestinal microbes contained. [Also see Perspective by Bouziat and Jabri] In healthy individuals, the intestinal microbiota cannot access the liver, spleen, or other peripheral tissues. Some pathogenic bacteria can reach these sites, however, and can induce a systemic immune response. How such compartmentalization is achieved is unknown. We identify a gut-vascular barrier (GVB) in mice and humans that controls the translocation of antigens into the blood stream and prohibits entry of the microbiota. Salmonella typhimurium can penetrate the GVB in a manner dependent on its pathogenicity island (Spi) 2–encoded type III secretion system and on decreased β-catenin–dependent signaling in gut endothelial cells. The GVB is modified in celiac disease patients with elevated serum transaminases, which indicates that GVB dismantling may be responsible for liver damage in these patients. Understanding the GVB may provide new insights into the regulation of the gut-liver axis.

  • BALB/c and C57BL/6 Mice Differ in Polyreactive IgA Abundance, which Impacts the Generation of Antigen-Specific IgA and Microbiota Diversity
    Floris Fransen, Elena Zagato, Elisa Mazzini, Bruno Fosso, Caterina Manzari, Sahar El Aidy, Andrea Chiavelli, Anna Maria D’Erchia, Maya K. Sethi, Oliver Pabst,et al.

    Elsevier BV
    The interrelationship between IgAs and microbiota diversity is still unclear. Here we show that BALB/c mice had higher abundance and diversity of IgAs than C57BL/6 mice and that this correlated with increased microbiota diversity. We show that polyreactive IgAs mediated the entrance of non-invasive bacteria to Peyer's patches, independently of CX3CR1(+) phagocytes. This allowed the induction of bacteria-specific IgA and the establishment of a positive feedback loop of IgA production. Cohousing of mice or fecal transplantation had little or no influence on IgA production and had only partial impact on microbiota composition. Germ-free BALB/c, but not C57BL/6, mice already had polyreactive IgAs that influenced microbiota diversity and selection after colonization. Together, these data suggest that genetic predisposition to produce polyreactive IgAs has a strong impact on the generation of antigen-specific IgAs and the selection and maintenance of microbiota diversity.

  • Dichotomy of short and long thymic stromal lymphopoietin isoforms in inflammatory disorders of the bowel and skin
    Giulia Fornasa, Katerina Tsilingiri, Flavio Caprioli, Fiorenzo Botti, Marina Mapelli, Stephan Meller, Andreas Kislat, Bernhard Homey, Antonio Di Sabatino, Angelica Sonzogni,et al.

    Elsevier BV
    Background Thymic stromal lymphopoietin (TSLP) is a cytokine with pleiotropic functions in the immune system. It has been associated with allergic reactions in the skin and lungs but also homeostatic tolerogenic responses in the thymus and gut. Objective In human subjects TSLP is present in 2 isoforms, short and long. Here we wanted to investigate the differential expression of the TSLP isoforms and discern their biological implications under homeostatic or inflammatory conditions. Methods We evaluated the expression of TSLPs in tissues from healthy subjects, patients with ulcerative colitis, patients with celiac disease, and patients with atopic dermatitis and on epithelial cells and keratinocytes under steady-state conditions or after stimulation. We then tested the immune activity of TSLP isoforms both in vitro and in vivo. Results We showed that TSLP isoforms are responsible for 2 opposite immune functions. The short isoform is expressed under steady-state conditions and exerts anti-inflammatory activities by affecting the capacity of PBMCs and dendritic cells to produce inflammatory cytokines. Moreover, the short isoform TSLP ameliorates experimental colitis in mice and prevents endotoxin shock. The long isoform of TSLP is proinflammatory and is only expressed during inflammation. The isoforms are differentially regulated by pathogenic bacteria, such as Salmonella species and adhesive-invasive Escherichia coli. Conclusions We have solved the dilemma of TSLP being both homeostatic and inflammatory. The TSLP isoform ratio is altered during several inflammatory disorders, with strong implications in disease treatment and prevention. Indeed, targeting of the long isoform of TSLP at the C-terminal portion, which is common to both isoforms, might lead to unwanted side effects caused by neutralization of the homeostatic short isoform.

  • Oral Tolerance Can Be Established via Gap Junction Transfer of Fed Antigens from CX3CR1<sup>+</sup> Macrophages to CD103<sup>+</sup> Dendritic Cells
    Elisa Mazzini, Lucia Massimiliano, Giuseppe Penna, and Maria Rescigno

    Elsevier BV
    Antigen-presenting cells (APCs) in the gut are apt at oral tolerance establishment at steady state and immunity after infection; complex tasks in an environment exposed to the inflammatory burden of the microbiota. Here we show an unanticipated division of labor among APCs for the establishment of oral tolerance. Chemokine receptor CX3CR1(+) macrophages were found to take up soluble fed antigens and quickly transfer them to CD103(+) dendritic cells (DCs). Antigen transfer occurred via a mechanism that was Connexin 43-dependent and required membrane transfer, indicating a physiological role of gap junctions in antigen presentation. Deletion of Connexin 43 in APCs affected antigen transfer and resulted in the inability of CD103(+) DCs to acquire and present antigens in vivo, to drive T regulatory cell differentiation and to induce tolerance to food antigens. This functional cooperation between intestinal phagocytes might be a mechanism to avoid the exposure of tolerogenic DCs to the intestinal microbiota.