Research Advances

Outstanding faculty in our division use cutting-edge research tools at the cellular, molecular and genetic levels to further understand mechanisms underlying immune-mediated diseases. Armed with this knowledge, our faculty identify novel translational insights that enable the development of new preventive and therapeutic strategies for diseases affecting children. This year has seen some fantastic discoveries published in first tier journals that also led to substantial increases in grant funding for the division.

Human severe congenital neutropenia (SCN), also known as Kostmann syndrome, is a disease of dysregulated myelopoiesis. Children with SCN have little to no neutrophils and suffer from life threatening bacterial and fungal infection, often in infancy. In an article published in Nature this year, the Grimes generated mouse models of SCN using patient-derived mutations in the growth factor independent-1 (GFI1) transcription factor. This is the first time that SCN patient mutations, when introduced into the mouse genome, generated homeostatic dysgranulopoiesis. The mice had few neutrophils, and were sensitive to pathogens that affect SCN patients. To delineate the impact of SCN mutations, they generated single-cell references for granulopoietic genomic states with linked epitopes, aligned mutant cells to their wild-type equivalent and identified differentially expressed genes and epigenetic loci. They find that Gfi1-target genes are frequently altered sequentially, as cells traverse successive states. These cell-state-specific insights facilitated genetic rescue of granulocytic specification but not post-commitment defects in the expression of innate-immune effectors, providing regulatory insights into granulocyte dysfunction. Moreover, this approach could extend to the analysis of not only congenital and acquired genetic changes, but also the therapeutic impact of new small molecules, where bulk cell analyses or current single cell analytic pipelines might gloss over rare but important cell states. The most important finding is that each cell state integrates the effect of genetic mutation differently, and this information is critical to both understanding disease and evaluating cures.

This year, the Miraldi lab published the first genome-scale transcriptional regulatory network (TRN) for intestinal innate lymphoid cells (ILCs) in Immunity. ILCs are a relatively recently discovered immune cell type with roles in pathogen defense, development and inflammatory diseases. The TRN contained >60,000 regulatory interactions between transcription factors (TFs) and target genes, identifying regulators specific to hallmark ILC phenotypes, including antigen presentation, cytokine signaling and circadian rhythm. Novel predictions, including potential TF therapeutic targets (regulating key disease response pathways), were experimentally validated in collaboration with Stephen Waggoner’s lab (Center for Autoimmune Genomics and Etiology) and in several independent studies citing this work. The intestinal ILC TRNs proved especially valuable to identifying potential therapeutic targets for inflammatory bowel disease, a disease that affects thousands of children in the U.S. each year.

This year, the Pasare lab made an unexpected discovery that effector or memory CD4 T cells provide two novel signals to antigen presenting myeloid cells (dendritic cells and macrophages) leads to production of bioactive IL-1 published in Nature Immunology. More importantly, this production of IL-1 by the cells of the innate immune system is completely independent of toll-like receptor activation as well as activation of the inflammasome pathways. TNF produced by T cells acts as signal 1 to drive pro-IL-1 production and FasL expressed in T cells acts as signal 2 to engage Fas on DCs and macrophages to induce Caspase-8 dependent cleavage of pro-IL-1 into bioactive IL-1. IL-1 plays a major role in inducing T cell mediated auto-immune diseases and, in collaboration with the Katz lab, they found that mice that lack TNFR or Fas are highly resistant to Experimental Auto-immune encephalitis (EAE), a mouse model of T cell driven auto-immune disease, multiple sclerosis (MS). These findings have major implications in suggesting TNFR-FAS-Caspase-8 as new pathways for therapeutic intervention.

Translational Breakthroughs

This year saw the culmination of almost 20 years of study by the Jordan lab into the role of a cytokine called interferon gamma (IFN-γ) in the fatal childhood immune disorder, hemophagocytic lymphohistiocytosis (HLH). As a trainee, Michael Jordan, MD, started studying HLH when he developed the first animal model of the disorder and made the first observations to explain how an apparent immune deficiency leads to the loss of normal immune regulation. As part of this work, Jordan and colleagues discovered that -γ causes HLH. Subsequent collaboration with a Swiss biopharmaceutical company led to the development of an IFN-γ blocking antibody called emapalumab. Jordan and an international team of collaborators studied this drug as the first rationally targeted treatment for HLH. Based on the results of this work, the FDA approved emapalumab in late 2018 for use in patients with HLH. The New England Journal of Medicine published “Emapalumab in Children with Primary Hemophagocytic Lymphohistiocytosis” in May, describing the findings of this international study which was co-led by Jordan.

Allergic disorders burden approximately 25% of people in developed countries; food allergy alone causes considerable morbidity and occasional mortality for approximately eight percent of children and four percent of adults in the U.S. The central pathogenic mechanism in allergy is most often mediated by an IgE – high affinity IgE receptor (FcεRI) – mast cell and basophil axis: allergen crosslinking of FcεRI -bound allergen-specific IgE on mast cells and basophils rapidly activates these cells to synthesize and release the vasoactive mediators, proteases, and cytokines that cause allergic signs and symptoms. However, limited FcεRI crosslinking can desensitize mast cells and basophils, making them resist activation by strong, allergen-induced crosslinking. In a paper recently published in Journal of Allergy and Clinical Immunology, the Finkelman and Khodoun labs applied this observation by treating humanized mice with monoclonal antibodies to human FcεRI, the IgE-binding chain of FcεRI in two ways that limit FcεRI crosslinking: (1) a rapid desensitization approach, in which allergic mice receive treatment with sequentially increasing quantities of anti-human FcεRI antibody, starting with a dose too low to cause mast cell- and basophil-mediated disease; and (2) treatment with a genetically engineered monovalent anti-human FcεRI Fab/Fc antibody, which has greatly reduced ability to crosslink FcεRI . Results of these NIH-supported studies show that both approaches safely, rapidly and completely suppress food allergy and anaphylaxis (allergic shock) in humanized mice, even in humanized mice made extremely sensitive. These observations have led them to engineer a chimeric monovalent anti-human FcεRI monoclonal antibody that has a fast on-rate and low FcεRI binding, which the study will test in non-human primate models of IgE-mediated anaphylaxis and, if successful, developed as a therapeutic for human allergy.

Faculty Development, Promotion and Recruitment

The Division of Immunology, along with the Center for Inflammation and Tolerance, recruited Rana Herro, PhD, as an assistant professor. Herro received her MS degree from the University of Rennes I-Microbiology Department in France. She went on to the University of Paris XI-Pasteur Institute-Agro Paris Tech-France to pursue her PhD studying the virulence genes in the food pathogen Listeria monocytogenes. She then went to The Scripps Research Institute-La Jolla, California to study TNF superfamily members and their role at the intersection of inflammation and fibrosis in the lab of Dr. Mick Croft. After a successful post-doctoral fellowship, Rana received an appointment as an instructor at the La Jolla Institute for Allergy and Immunology where she honed her work on TNF family members LIGHT and TL1A, showing that TL1A was critical for fibrosis associated with asthma and idiopathic pulmonary fibrosis. Further, she made the novel discovery that LIGHT is critical for the fibrotic response that occurs in IPF and systemic sclerosis as well as atopic dermatitis and eczema. The central theme of her work is to uncover the molecular and cellular mechanisms by which TNF family members promote fibrosis and inflammation in diseases affecting children (asthma, myelofibrosis, non-alcoholic steatohepatitis, and biliary atresia, amongst others).

Congratulations to Theresa Alenghat, VMD, PhD, who received a Cincinnati Children's Faculty Research Achievement Award, named a CCHRF Endowed Scholar and promoted to associate professor with tenure.

Congratulations to Senad Divanovic, PhD, for becoming a CCHRF Endowed Scholar.