Metabolism and immune responses of striped hamsters to ectoparasite challenges: insights from transcriptomic analysis

Abstract

Introduction: The striped hamster, often parasitized by ectoparasites in nature, is an ideal model for studying host-ectoparasite molecular interactions. Investigating the response to ectoparasites under laboratory conditions helps elucidate the mechanism of host adaptations to ectoparasite pressure.

Methods: Using transcriptome sequencing, we analyzed gene expression in striped hamsters after short-term (3 days) and long-term (28 days) flea (Xenopsylla cheopis) parasitism. Differentially expressed genes (DEGs) were identified and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Hub genes were pinpointed using protein-protein interaction (PPI) network analysis and the MCODE in Cytoscape. Gene Set Enrichment Analysis (GSEA) was used to further clarify the functional pathways of these hub genes. Validation of DEGs was performed via RT-qPCR. Additionally, the concentrations of reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were determined using specific enzyme-linked immunosorbent assay (ELISA) detection kits for hamsters.

Results: GO analysis revealed that during early parasitism, hosts primarily responded to the ectoparasites by adjusting the expression of genes related to metabolic functions. As parasitism persisted, the immune response became prominent, activating various immune pathways against ectoparasites. KEGG analysis confirmed the ongoing roles of metabolism and immunity. Notably, the chemical carcinogenesis - reactive oxygen species pathway was upregulated during flea parasitism, with downregulation of hub genes ATP5MC1 and ATP5MC2, highlighting the importance of mitochondrial function in oxidative stress. ELISA findings revealed that on day 3, flea parasitism groups showed elevated ROS expression and reduced SOD and CAT levels compared to the control group. By day 28, only SOD expression showed a significant decrease in both parasitism groups.

Conclusion: This study uncovered the dynamic changes in metabolism and immune responses of striped hamsters parasitized by Xenopsylla cheopis. Hosts adjust their physiological and immune states to optimize survival strategies during different ectoparasite stages, enhancing our understanding of host-ectoparasite interactions. This also paves the way for further research into how hosts regulate complex biological processes in response to ectoparasite challenges.

Keywords: ectoparasites parasitism; immunity; metabolism; striped hamsters; transcriptome analysis.

Figure 1

Weight changes and influencing factors of striped hamsters in each group. (A) represents the weight changes of striped hamsters in the control group, low-intensity group and high-intensity group after 3, 7, 14 and 28 days of the experiment. On the horizontal axis, the first digit of each number represents the number of days, the second digit represents the group (1 represents the control group, 2 represents the low-intensity group, 3 represents the high-intensity group), and the third digit represents the hamster number within the group. (B) represents the influence of parasitic days, number of parasitic fleas, number of body fleas, number of nest fleas and food supply amount on the weight changes in hamsters, respectively. The variables with red dots are the influencing variables with P < 0.05.

Figure 2

Venn diagrams and heat maps of DEGs in striped hamsters with different flea parasitism intensities during different time periods. (A, B) Heat maps of DEGs in striped hamsters with different flea parasitism intensities on the third and twenty-eighth days. The X-axis in the figure represents the sample name, and the Y-axis represents the normalized values of the FPKM of DEGs. Red represents upregulated genes, while blue represents downregulated genes. (C-F) The Venn diagrams illustrating the overlapping genes in every two comparison groups. 3_1 represents the control group on the third day. 3_2 represents the low-intensity flea parasitism group on the third day. 3_3 represents the high-intensity flea parasitism group on the third day. 28_1 represents the control group on the 28th day. 28_2 represents the low-intensity flea parasitism group on the 28th day. 28_3 represents the high-intensity flea parasitism group on the 28th day.

Figure 3

Network Diagram of GO terms enrichment analysis of DEGs. (A-C) Biological processes (BP), cellular components (CC) and molecular function (MF) of early-stage intensity-dependent comparison group. (D-F) BP, CC and MF of late-stage intensity-dependent comparison group. (G-I) BP, CC and MF of low-intensity time-dependent comparison group. (J-L) BP, CC and MF of high-intensity time-dependent comparison group.

Figure 4

Cluster tree diagram of KEGG pathway enrichment analysis of DEGs. (A) Early-stage intensity-dependent comparison group. (B) Late-stage intensity-dependent comparison group. (C) Low-intensity time-dependent comparison group. (D) High-intensity time-dependent comparison group.

Figure 5

PPI network analysis displayed 110 DEGs related to metabolism and immunity after hiding disconnected nodes in the network. The red circles represent the 23 hub genes obtained through MCODE analysis.

Figure 6

GSEA related to hub genes. 3 days of low-intensity group vs. control group. (B) 3 days of high-intensity group vs. low-intensity group. (C) 28 days low-intensity group vs. control group. (D) 28 days high-intensity group vs. low-intensity group.

Figure 7

Pathways related to chemical carcinogenesis - reactive oxygen species.

Figure 8

Validation of DEGs between the low-intensity flea parasitism group and the control group after 28 days by RT-qPCR. The x-axis represents the DEGs name, and the y-axis represents the log2 fold change.

Figure 9

The concentrations of ROS, SOD, GSH-Px and CAT analyzed by ELISA assay *P < 0.05; ns, no significance.