Background: Coronavirus disease 19 (COVID-19) is an emerging infectious disease caused by SARS-CoV-2. Anti-viral immune response is crucial to achieve pathogen clearance, however in some patients an excessive and aberrant host immune response can lead to an acute respiratory distress syndrome. The comprehension of the mechanisms that regulate pathogen elimination, immunity, and pathology is essential to better characterize disease progression and widen the spectrum of therapeutic options. Methods: We performed a flow cytometric characterization of immune cells subsets from 30 COVID-19 patients and correlated these data with clinical outcomes. Results: COVID-19 patients showed decreased numbers of circulating T, B and NK cells, and exhibited a skewing of CD8+ T cells towards a terminally differentiated/senescent phenotype. In agreement, T CD4+, T CD8+ but also NK cells displayed reduced anti-viral cytokine production capability. Moreover, a reduced cytotoxic potential was identified in COVID-19 patients, particularly in those that required intensive care. The latter group of patients showed also increased serum IL-6 levels, that correlated to the frequency of granzyme-expressing NK cells. Off-label treatment with tocilizumab restored the cytotoxic potential of NK cells. Conclusion: In conclusion, the association between IL-6 serum levels and the impairment of cytotoxic activity suggests the possibility that targeting this cytokine may restore anti-viral mechanisms. Funding: This study was supported by funds of Dept. of Experimental and Clinical Medicine of University of Florence (ex-60%) derived from Ministero dell’Istruzione, dell’Università e della Ricerca (Italy).
Alessio Mazzoni, Lorenzo Salvati, Laura Maggi, Manuela Capone, Anna Vanni, Michele Spinicci, Jessica Mencarini, Roberto Caporale, Benedetta Peruzzi, Alberto Antonelli, Michele Trotta, Lorenzo Zammarchi, Luca Ciani, Leonardo Gori, Chiara Lazzeri, Andrea Matucci, Alessandra Vultaggio, Oliviero Rossi, Fabio Almerigogna, Paola Parronchi, Paolo Fontanari, Federico Lavorini, Adriano Peris, Gian Maria Rossolini, Alessandro Bartoloni, Sergio Romagnani, Francesco Liotta, Francesco Annunziato, Lorenzo Cosmi
The absence of alloantibodies is a feature of transplantation tolerance. Although the lack of T cell help has been evoked to explain this absence, herein we provide evidence for B cell–intrinsic tolerance mechanisms. Using a murine model of heart tolerance, we showed that alloreactive B cells were not deleted but rapidly lost their ability to differentiate into germinal center B cells and secrete donor-specific antibodies. We inferred that tolerant alloreactive B cells retained their ability to sense alloantigen because they continued to drive T cell maturation into CXCR5+PD-1+ T follicular helper cells. Unexpectedly, dysfunctional alloreactive B cells acquired the ability to inhibit antibody production by new naive B cells in an antigen-specific manner. Thus, tolerant alloreactive B cells contribute to transplantation tolerance by foregoing germinal center responses while retaining their ability to function as antigen-presenting cells and by actively suppressing de novo alloreactive B cell responses.
Stella H.W. Khiew, Dharmendra Jain, Jianjun Chen, Jinghui Yang, Dengping Yin, James S. Young, Alexander Dent, Roger Sciammas, Maria-Luisa Alegre, Anita S. Chong
Myelopoiesis is invariably present, and contributes to pathology, in animal models of graft versus host disease (GVHD). In humans, a rich inflammatory infiltrate bearing macrophage markers has also been described in histological studies. In order to determine the origin, functional properties and role in pathogenesis of these cells, we isolated single cell suspensions from acute cutaneous GVHD and subjected them to genotype, transcriptome and in vitro functional analysis. A donor-derived population of CD11c+CD14+ cells was the dominant population of all leukocytes in GVHD. Surface phenotype and nanostring gene expression profiling indicated the closest steady-state counterpart of these cells to be monocyte-derived macrophages. In GVHD, however, there was upregulation of monocyte antigens SIRPα and S100A8/9, and transcripts associated with leukocyte trafficking, pattern recognition, antigen presentation, and co-stimulation. Isolated GVHD macrophages stimulated greater proliferation and activation of allogeneic T cells, and secreted higher levels of inflammatory cytokines than their steady-state counterparts. In HLA-matched mixed leukocyte reactions, we also observed differentiation of activated macrophages with a similar phenotype. These exhibited cytopathicity to a cell line and mediated pathological damage to skin explants, independently of T cells. Together, these results define the origin, functional properties and potential pathogenic roles of human GVHD macrophages.
Laura Jardine, Urszula Cytlak, Merry Gunawan, Gary Reynolds, Kile Green, Xiao-nong Wang, Sarah Pagan, Maharani Paramitha, Christopher A. Lamb, Anna Long, Erin Hurst, Smeera Nair, Graham H. Jackson, Amy Publicover, Venetia Bigley, Muzlifah Haniffa, AJ Simpson, Matthew Collin
Despite the widespread use of antibiotics, bacterial pneumonias in donors strongly predispose to the fatal syndrome of primary graft dysfunction (PGD) following lung transplantation. We report that bacterial endotoxin persists in human donor lungs after pathogen is cleared with antibiotics and is associated with neutrophil infiltration and PGD. In mouse models, depletion of tissue-resident alveolar macrophages (TRAM) attenuated neutrophil recruitment in response to endotoxin as shown by compartmental staining and intravital imaging. Bone marrow chimeric mice revealed that neutrophils were recruited by TRAM through activation of TLR4 in a MyD88-dependent manner. Intriguingly, low levels of endotoxin, insufficient to cause donor lung injury, promoted TRAM-dependent production of CXCL2, increased neutrophil recruitment, and led to PGD, which was independent of donor non-classical monocytes. Reactive oxygen species (ROS) increased in human donor lungs starting from the warm-ischemia phase and were associated with increased transcription and translocation to the plasma membrane of TLR4 in donor TRAM. Consistently, scavenging ROS or inhibiting their production to prevent TLR4 transcription/translocation or blockade of TLR4 or co-receptor CD14 on donor TRAM prevented neutrophil recruitment in response to endotoxin and ameliorated PGD. Our studies demonstrate that residual endotoxin after successful treatment of donor bacterial pneumonia promotes PGD through ischemia-reperfusion-primed donor TRAM..
Mahzad Akbarpour, Emilia Lecuona, Stephen Chiu, Qiang Wu, Melissa Querrey, Ramiro Fernandez, Felix Luis Nunez-Santana, Haiying Sun, Sowmya Ravi, Chitaru Kurihara, James M. Walter, Nikita Joshi, Ziyou Ren, Scott C. Roberts, Alan R. Hauser, Daniel Kreisel, Wenjun Li, Navdeep Chandel, Alexander V. Misharin, Thalachallour Mohanakumar, G.R. Scott Budinger, Ankit Bharat
Understanding tumor resistance to T cell immunotherapies is critical to improve patient outcomes. Our study revealed a role for transcriptional suppression of the tumor-intrinsic HLA class I (HLA-I) antigen processing and presentation machinery (APM) in therapy resistance. Low HLA-I APM mRNA levels in melanoma metastases prior to immune checkpoint blockade (ICB) correlated with non-responsiveness to therapy and poor clinical outcome. Patient-derived melanoma cells with silenced HLA-I APM escaped recognition by autologous CD8+ T cells. However, targeted activation of the innate immunoreceptor RIG-I initiated de novo HLA-I APM transcription thereby overcoming T cell resistance. Antigen presentation was restored in interferon (IFN)-sensitive but also immunoedited IFN-resistant melanoma models through RIG-I-dependent stimulation of an IFN-independent salvage pathway involving IRF1 and IRF3. Likewise, enhanced HLA-I APM expression was detected in RIG-I (DDX58)-high melanoma biopsies, correlating with improved patient survival. Induction of HLA-I APM by RIG-I synergized with antibodies blocking PD-1 and TIGIT inhibitory checkpoints in boosting the anti-tumor T cell activity of ICB non-responders. Overall, the herein identified IFN-independent effect of RIG-I on tumor antigen presentation and T cell recognition proposes innate immunoreceptor targeting as a strategy to overcome intrinsic T cell resistance of IFN-sensitive and IFN-resistant melanomas and improve clinical outcomes in immunotherapy.
Lina Such, Fang Zhao, Derek Liu, Beatrice Thier, Vu Thuy Khanh Le-Trilling, Antje Sucker, Christoph Coch, Natalia Pieper, Sebastian Howe, Hilal Bhat, Halime Kalkavan, Cathrin Ritter, Robin Brinkhaus, Selma Ugurel, Johannes Köster, Ulrike Seifert, Ulf Dittmer, Martin Schuler, Karl Sebastian Lang, Thomas A Kufer, Gunther Hartmann, Jürgen Christian Becker, Susanne Horn, Soldano Ferrone, David Liu, Eliezer M. Van Allen, Dirk Schadendorf, Klaus Griewank, Mirko Trilling, Annette Paschen
Mothers living near high-traffic roads before or during pregnancy have increased odds of having children with asthma. Mechanisms are unknown. Using a mouse model, here we showed that maternal exposure to diesel exhaust particles (DEP) predisposed offspring to allergic airway disease/AAD (murine counterpart of human asthma) through programming of their NK cells; predisposition to AAD did not develop in ‘DEP’ pups that lacked NK cells and was induced in normal pups receiving NK cells from wild type ‘DEP’ pups. “DEP’ NK cells expressed GATA3 and co-secreted IL-13 and the ‘killer’ protease granzyme B in response to allergen challenge. Extracellular granzyme B did not kill but instead it stimulated protease-activated receptor 2 (PAR2) to cooperate with IL-13 in the induction of IL-25 in airway epithelial cells. Through loss-of-function and reconstitution experiments in pups, we showed that NK cells and granzyme B were required for IL-25 induction and activation of the type-2 immune response, and IL-25 mediated NK cell effects on type-2 response and AAD. Lastly, experiments using human cord blood and airway epithelial cells suggested that DEP might induce an identical pathway in humans. Collectively, we described an NK cell-dependent endotype of AAD that emerged in early life as a result of maternal exposure to DEP.
Qian Qian, Bidisha Paul Chowdhury, Zehua Sun, Jerica Lenberg, Rafeul Alam, Eric Vivier, Magdalena M. Gorska
Mendelian susceptibility to mycobacterial disease (MSMD) is characterized by a selective predisposition to clinical disease caused by the Bacille Calmette-Guérin (BCG) vaccine and environmental mycobacteria. The known genetic etiologies of MSMD are inborn errors of IFN-γ immunity due to mutations of 15 genes controlling the production of or response to IFN-γ. Since the first MSMD-causing mutations were reported in 1996, biallelic mutations in the genes encoding IFN-γ receptor 1 (IFN-γR1) and IFN-γR2 have been reported in many patients of diverse ancestries. Surprisingly, mutations of the gene encoding the IFN-γ cytokine itself have not been reported, raising the remote possibility that there might be other agonists of the IFN-γ receptor. We describe 2 Lebanese cousins with MSMD, living in Kuwait, who are both homozygous for a small deletion within the IFNG gene (c.354_357del), causing a frameshift that generates a premature stop codon (p.T119Ifs4*). The mutant allele is loss of expression and loss of function. We also show that the patients’ herpesvirus Saimiri–immortalized T lymphocytes did not produce IFN-γ, a phenotype that can be rescued by retrotransduction with WT IFNG cDNA. The blood T and NK lymphocytes from these patients also failed to produce and secrete detectable amounts of IFN-γ. Finally, we show that human IFNG has evolved under stronger negative selection than IFNGR1 or IFNGR2, suggesting that it is less tolerant to heterozygous deleterious mutations than IFNGR1 or IFNGR2. This may account for the rarity of patients with autosomal-recessive, complete IFN-γ deficiency relative to patients with complete IFN-γR1 and IFN-γR2 deficiencies.
Gaspard Kerner, Jérémie Rosain, Antoine Guérin, Ahmad Al-Khabaz, Carmen Oleaga-Quintas, Franck Rapaport, Michel J. Massaad, Jing-Ya Ding, Taushif Khan, Fatima Al Ali, Mahbuba Rahman, Caroline Deswarte, Rubén Martinez-Barricarte, Raif S. Geha, Valentine Jeanne-Julien, Diane Garcia, Chih-Yu Chi, Rui Yang, Manon Roynard, Bernhard Fleckenstein, Flore Rozenberg, Stéphanie Boisson-Dupuis, Cheng-Lung Ku, Yoann Seeleuthner, Vivien Béziat, Nico Marr, Laurent Abel, Waleed Al-Herz, Jean-Laurent Casanova, Jacinta Bustamante
The microbiome provides resistance to infection. However, mechanisms for this are poorly understood. Here we demonstrate in a murine model that colonization with the intestinal bacterium Clostridium scindens provided protection from Entamoeba histolytica colitis via innate immunity. Introduction of C. scindens into the gut microbiota epigenetically altered and expanded bone marrow granulocyte-monocyte-progenitors (GMPs) and resulted in increased intestinal neutrophils with subsequent challenge with E. histolytica. Introduction of C. scindens alone was sufficient to expand GMPs in gnotobiotic mice. Adoptive transfer of bone-marrow from C. scindens colonized-mice into naïve-mice protected against amebic colitis and increased intestinal neutrophils. Children without E. histolytica diarrhea also had a higher abundance of Lachnoclostridia. Because of the known ability of the Lachnoclostridia C. scindens to metabolize the bile salt cholate, we measured deoxycholate and discovered that it was increased in the sera of C. scindens colonized specific pathogen free and gnotobiotic mice, as well as in children protected from amebiasis. Administration of deoxycholate alone (in the absence of C. scindens) increased GMPs and provided protection from amebiasis. We have discovered a mechanism by which C. scindens and the microbially-metabolized bile salt deoxycholic acid alter hematopoietic precursors and provide innate protection from later infection with Entamoeba histolytica.
Stacey L. Burgess, Jhansi L. Leslie, Md. Jashim Uddin, David Noah Oakland, Carol A. Gilchrist, G. Brett Moreau, Koji Watanabe, Mahmoud M. Saleh, Morgan Simpson, Brandon A. Thompson, David T. Auble, Stephen D. Turner, Natasa Giallourou, Jonathan Swann, Zhen Pu, Jennie Z. Ma, Rashidul Haque, William A. Petri, Jr.
Hepatocellular carcinoma (HCC) is difficult to detect, carries a poor prognosis, and is one of few cancers with an increasing yearly incidence. Molecular defects in complement factor H (CFH), a critical regulatory protein of the complement alternative pathway (AP), are typically associated with inflammatory diseases of the eye and kidney. Little is known regarding the role of CFH in controlling complement activation with the liver. While studying aging CFH-deficient (fH–/–) mice, we observed spontaneous hepatic tumor formation in more than 50% of aged fH–/– males. Examination of fH–/– livers (3–24 months) for evidence of complement-mediated inflammation revealed widespread deposition of complement activation fragments throughout the sinusoids, elevated transminase levels, increased hepatic CD8+ and F4/80+ cells, overexpress of hepatic mRNA associated with inflammatory signaling pathways, steatosis and increased collagen deposition. Immunostaining of human HCC biopsies revealed extensive deposition of complement fragments within the tumors. Interrogation of the Cancer Genome Atlas also revealed that increased CFH mRNA expression is associated with improved survival in HCC patients, whereas mutations are associated with worse survival. These results indicate that CFH is critical for controlling complement activation in the liver, and in its absence, AP activation leads to chronic inflammation and promotes hepatic carcinogenesis.
Jennifer Laskowski, Brandon Renner, Matthew C. Pickering, Natalie J. Serkova, Peter M. Smith-Jones, Eric T. Clambey, Raphael A. Nemenoff, Joshua M. Thurman
Patients with respiratory syncytial virus (RSV) infection exhibit enhanced susceptibility to subsequent pneumococcal infections. However, the underlying mechanisms involved in this increased susceptibility remain unclear. Here, we identified potentially novel cellular and molecular cascades triggered by RSV infection to exacerbate secondary pneumococcal pneumonia. RSV infection stimulated the local production of growth arrest–specific 6 (Gas6). The Gas6 receptor Axl was crucial for attenuating pneumococcal immunity in that the Gas6/Axl blockade fully restored antibacterial immunity. Mechanistically, Gas6/Axl interaction regulated the conversion of alveolar macrophages from an antibacterial phenotype to an M2-like phenotype that did not exhibit antibacterial activity, and the attenuation of caspase-1 activation and IL-18 production in response to pneumococcal infection. The attenuated IL-18 production failed to drive both NK cell–mediated IFN-γ production and local NO and TNF-α production, which impair the control of bacterial infection. Hence, the RSV-mediated Gas6/Axl activity attenuates the macrophage-mediated protection against pneumococcal infection. The Gas6/Axl axis could be a potentially novel therapeutic target for RSV-associated secondary bacterial infection.
Takehiko Shibata, Airi Makino, Ruiko Ogata, Shigeki Nakamura, Toshihiro Ito, Kisaburo Nagata, Yoshihiko Terauchi, Taku Oishi, Mikiya Fujieda, Yoshimasa Takahashi, Manabu Ato