Medical Journal Reviews

The International Eosinophil Society (IES) selects articles on a monthly basis for their importance to scientists and clinicians interested in the eosinophil. We welcome Medical Journal Review submissions from IES Members for consideration. Your review should be clear, compelling, and appeal to our international membership.

Submit Review Here Submission Guidelines

September 2024

Eosinophils on the move: how diet impacts immune cells in the intestine

Article: Nutrient-derived signals regulate eosinophil adaptation to the small intestine
Kutyavin VI, Korn LL, Medzhitov R
National Academy of Sciences. 2024 January

Reviewed by Clotilde Lacroix, University of Bonn, Germany

Eosinophils can be involved in homeostasis and tissue-specific functions, which are regulated by local signals. The study by Kutyavin, Korn, and Medzhitov reveals that nutrient-derived signals regulate the adaptation of eosinophils in the small intestine (SI).

Using flow cytometry and the BrdU pulse-chase technique, Kutyavin et al. nicely demonstrate the existence of three eosinophil subpopulations in the SI: a young subset located around the crypts expressing α4β7; an intermediate subset lacking α4β7 and CD22 expression; and a mature subset, expressing CD22, found in the upper part of the villi. Through bulk RNA sequencing, they showed that this mature subset is best adapted to the SI microenvironment. Interestingly, this mature CD22+ subset, as well as the younger α4β7+ subset, appears to correspond to Clec4a4 positive and negative subsets previously identified in the work of Wang et al. (Wang WL, et al. Proc Natl Aca Sci U S A. 2022 Jun;119(23)). Additionally, Kutyavin et al highlight the role of amino acids and retinoic acid (RA) signaling in the accumulation and survival of SI-resident eosinophils. Using animal models, they demonstrated that disrupting the RA pathway by inhibiting its receptor, RAR, induces selective loss and increased turnover of the mature eosinophil subset. Furthermore, as RA is a nutrient-derived signal, the study showed that the composition of the diet, particularly the quantity of amino acids, has a significant impact on eosinophil adaptation to the SI environment. These findings echoes with the recent work by Diny et al. (Diny NL, et al. J Exp Med. 2022 Apr;219(4)), which also emphasized the crucial role of nutrients in the tissue adaptation of eosinophils in the SI.

Kutyavin et al.'s study significantly advances our understanding of eosinophil tissue adaptation in the SI. It provides valuable insights into the role of nutrient-derived signals, such as RA and amino acids, in regulating eosinophil populations. The study also raises interesting questions, such as the source of RA, the specific amino acids involved, and whether the enhanced survival of mature eosinophils is a direct effect of RA or mediated indirectly, possibly through the induction of markers associated with a longer lifespan. Given CD22’s previously described negative role of regulating small intestinal eosinophil levels (Wen et al, J. Immunol. 188, 1075–1082 (2012), there remains much to further uncover.

Clotilde LacroixClotilde Lacroix is a PhD candidate in Dr Nicola Diny's group at the Institute of Clinical Chemistry and Clinical Pharmacology in Bonn, Germany. She is interested in investigating the phenotype, function and adaptation of eosinophils in different tissues. She graduated with a master's degree in medical biology from the University of Lausanne, Switzerland. During her master's internship in Professor Tatiana Petrova's group, she worked on vascularisation and the formation of tertiary lymphoid structures in colon cancer.

 


The origin of eosinophils: Key advances in understanding their development and expansion

Article: Single-cell proteomics and transcriptomics capture eosinophil development and identify the role of IL-5 in their lineage transit amplification
Jorssen J, Hulst GV, Mollers K, Pujol J, Petrellis G, Baptista AP, Schetters S, Baron F, Caers J, Lambrecht BN, Dewals BG, Bureau F, Desmet CJ
Immunity. 2024 May

Reviewed by Alexandre Ecrement, University of Franche-Comté, Franche-Comté, France

The development, maturation and expansion mechanisms of eosinophils are less understood compared to other immune cells. This original article provides key insight into human and murine eosinophilopoiesis.

The study utilized single-cell RNA sequencing and single-cell proteomics combined with high-dimensional flow cytometry to capture the early stages of murine eosinophil development from bone marrow progenitors. It demonstrated that human eosinophilopoiesis closely resembles that of mice. Furthermore, the researchers showed that the expansion of eosinophil progenitors in models of eosinophilic conditions, such as asthma, eosinophilic esophagitis, and hypereosinophilic syndrome, is driven by increased transit amplification, a process where these progenitor cells rapidly multiply during their developmental phase before maturing into fully functional eosinophils, which relies on the slower acquisition of a fully mature phenotype and increased, prolonged proliferation capacity.

Using transgenic IL-5Rα reporter mice and conducting neutralization experiments, the authors demonstrated that IL-5 induces the stimulation and proliferation of eosinophilic progenitors but does not haved a role in the maturation process. This confirms previous observations that IL-5 deficient mice and asthmatics patients treated with anti-IL5 antibodies have a significant reduction in bone marrow and blood eosinophilia but the maturation of residual eosinophils remains uncompromised.This article is noteworthy due to its comprehensive approach, combining advanced single-cell technologies, including single-cell RNA sequencing and high-dimensional flow cytometry, allowing significant advancement in identifying the stages of eosinophil maturation. However, the study did not consider conditions of human eosinophilia nor examine precursors in all the biological environments, from the bone marrow to the blood.

Alexandre EcrementAlexandre Ecrement is a PhD candidate at University of Franche-Comté in France in the laboratory INSERM UMR 1098 RIGHT under the supervision of Pr Cindy Barnig. His research focuses on the role and functions of eosinophils in asthma and their interaction with the bronchial epithelium. He is currently working on a cohort of patients to characterize eosinophils in respiratory diseases, aiming to elucidate their specific role in the pathophysiology of asthma.

 

 


Past Reviews

August 2024

Utility of eosinophil peroxidase as a biomarker of eosinophilic inflammation in asthma
Reviewed by Nicholas Genovese, Jefferson Einstein Philadelphia Hospital, Pennsylvania, United States

July 2024

Eosinophil Depletion with Benralizumab for Eosinophilic Esophagitis
Reviewed by Mario Ynga-Durand, MD, PhD, Cincinnati Children's Hospital Medical Center, Ohio, United States

June 2024

Subsets of sputum eosinophils in asthma exacerbations
Reviewed by Jakub Novosad, MD, PhD, Institute of Clinical Immunology and Allergy, University Hospital, Hradec Kralove, Czech Republic

April 2024

Eosinophils potentiate anti-bacterial immunity
Reviewed by Roopa Hebbandi Nanjundappa, MSc, PhD, Dalhousie University, Halifax, Canada

March 2024

Nourishing insights: diet-driven adaptation of eosinophils
Reviewed by Krishan Chhiba, MD, PhD, Northwestern University, Chicago, United States

February 2024

Eosinophils identified as a major contributor to bone homeostasis via eosinophil peroxidase activity
Reviewed by Nana-Fatima Haruna, PhD Candidate, Northwestern University, Chicago, United States

January 2024

Transcriptomic profiling of the acute mucosal response to local food injections in adults with eosinophilic esophagitis
Reviewed by Eva Gruden, Pharmacist, Medical University of Graz, Austria

December 2023

Bordetella spp. block eosinophil recruitment to suppress the generation of early mucosal protection
Reviewed by Rachael FitzPatrick, PhD Candidate, Reynolds Laboratory at the University of Victoria, Canada

October 2023

Neuromedin U programs eosinophils to promote mucosal immunity of the small intestine
Reviewed by Beth Jacobson, PhD with input from Marc Rothenberg, MD, PhD

Chronic HDM exposure shows time-of-day and sex-based differences in inflammatory response associated with lung circadian clock disruption
Reviewed by Julia Teppan, MSc.Ph.D.Student

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