• Single-cell transcriptome anal...

*Result*: Single-cell transcriptome analysis reveals a cellular immune response in common carp (Cyprinus carpio) infected with Aeromonas hydrophila.

Title:
Single-cell transcriptome analysis reveals a cellular immune response in common carp (Cyprinus carpio) infected with Aeromonas hydrophila.
Authors:
Shi X; Henan Province Engineering Research Center of Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Xinxiang, 453007, China; North Henan Medical University, Xinxiang, 453003, China., Ji G; North Henan Medical University, Xinxiang, 453003, China., Liu D; North Henan Medical University, Xinxiang, 453003, China., Zhao T; North Henan Medical University, Xinxiang, 453003, China., Tian S; College of Life and Geographic Sciences, Key Laboratory of Biological Resources and Ecology of Pamirs Plateauin Xinjiang Uygur Autonomous Region, Kashi University, Kashi, 844000, China., Li S; College of Life and Geographic Sciences, Key Laboratory of Biological Resources and Ecology of Pamirs Plateauin Xinjiang Uygur Autonomous Region, Kashi University, Kashi, 844000, China., Kong X; Henan Province Engineering Research Center of Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Xinxiang, 453007, China. Electronic address: xhkong@htu.cn.
Source:
International journal of biological macromolecules [Int J Biol Macromol] 2026 Mar; Vol. 349, pp. 150936. Date of Electronic Publication: 2026 Feb 13.
Publication Type:
Journal Article
Language:
English
Journal Info:
Publisher: Elsevier Country of Publication: Netherlands NLM ID: 7909578 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1879-0003 (Electronic) Linking ISSN: 01418130 NLM ISO Abbreviation: Int J Biol Macromol Subsets: MEDLINE
Imprint Name(s):
Publication: Amsterdam : Elsevier
Original Publication: Guildford, Eng., IPC Science and Technology Press.
MeSH Terms:
Carps*/immunology , Carps*/microbiology , Carps*/genetics , Aeromonas hydrophila*/immunology , Gram-Negative Bacterial Infections*/immunology , Gram-Negative Bacterial Infections*/veterinary , Gram-Negative Bacterial Infections*/genetics , Gram-Negative Bacterial Infections*/microbiology , Fish Diseases*/immunology , Fish Diseases*/microbiology , Fish Diseases*/genetics , Immunity, Cellular*/genetics , Single-Cell Analysis* , Gene Expression Profiling* , Transcriptome*, Macrophages/immunology ; Macrophages/metabolism ; Head Kidney/immunology ; Head Kidney/microbiology ; Animals ; Single-Cell Gene Expression Analysis
Contributed Indexing:
Keywords: Aeromonas hydrophila; Cyprinus carpio; Immune response; Macrophage heterogeneity; Single-cell transcriptome
Entry Date(s):
Date Created: 20260215 Date Completed: 20260306 Latest Revision: 20260306
Update Code:
20260306
DOI:
10.1016/j.ijbiomac.2026.150936
PMID:
41692207
Database:
MEDLINE

*Further Information*

*This study aimed to employ single-cell RNA sequencing technology to comprehensively investigate the cellular immune response mechanisms in the key immune organ, the head kidney, of common carp (Cyprinus carpio) following infection with Aeromonas hydrophila, with a particular focus on the heterogeneity, differentiation, and molecular regulatory networks of macrophages at the cellular level.
Method: An infection model in common carp was established via intraperitoneal injection of A.hydrophila and validated using conventional methods, including pathological examination, serum immune enzyme assays, and immunohistochemistry. The core approach applied single-cell RNA sequencing to the head kidney tissues of infected and control fish. Bioinformatic analyses included cell clustering, high-dimensional weighted gene co-expression network analysis, pseudotime analysis, and cell-to-cell communication analysis to track immune cell dynamics. Proteomics was used to corroborate these key findings.
Results: Infection induced characteristic pathological signs in common carp, altered serum immune-enzyme activities, and caused inflammatory tissue damage. Single-cell transcriptomics of the head kidney revealed ten distinct macrophage subpopulations, with a significant post-infection shift in the proportion of CXCL19-expressing cells. CXCL19<sup>+</sup> macrophages were further divided into two functionally distinct groups: Macro_cxcl19_NEW1, an M2-like subset with anti-inflammatory and immunosuppressive features, and Macro_cxcl19_NEW2, an immune-activating subset. Pseudotime analysis indicated a differentiation trajectory from NEW2 to NEW1 and highlighted candidate regulators, including cfbl (complement factor B), npm1a (nucleophosmin), prkaa1.1 (AMPK catalytic subunit), and selenow1. These findings were confirmed by proteomics, demonstrating significant downregulation of the CFBL protein in infected fish.
Conclusions: This study provides, for the first time at single-cell resolution, a systematic map of head kidney immune responses to bacterial infection in Common carp. This revealed substantial macrophage heterogeneity and a central role for these cells in immune regulation. The identified subpopulations and regulatory genes offer new insights into fish cellular immunity and establish a molecular foundation for targeted strategies against Aeromonas hydrophila, including immune enhancers and disease-resistant breeding.
(Copyright © 2026 Elsevier B.V. All rights reserved.)*

*Declaration of competing interest We confirm that this manuscript is original and has not been published elsewhere nor is it currently under consideration for publication elsewhere. All the mentioned authors above have seen and approved the submission of the current manuscript. This manuscript is being submitted to your journal on exclusive basis. The authors declare no conflict of interest.*