Immunity and Immunoregulation in Helminth Infections

Background and Aim: The immunological interactions between soil-transmitted helminths (STHs) and herpes simplex virus type 2 (HSV-2), particularly in the context of co-infection, are poorly understood. Next-generation sequencing (NGS) offers a powerful approach to explore these complex immune responses and uncover potential therapeutic targets. This study leveraged NGS and bioinformatic tools to investigate transcriptional changes and immunological pathways in female genital tract (FGT) tissues of BALB/c mice acutely infected with Nippostrongylus brasiliensis (Nb), HSV-2, or co-infected. Methods: Total RNA was harvested from FGT tissues of BALB/c mice infected with Nb, HSV-2, co-infected with both pathogens, and uninfected controls. Differentially expressed genes (DEGs) were identified by comparing uninfected versus infected FGT tissues in R using edgeR and limma packages. Immune-related genes were identified by intersecting DEGs in each group-wise comparison with immune function gene sets derived from the Mouse Genome Informatics (MGI) database. Functional and pathway enrichment analyses were performed with g: Profiler and protein–protein interaction networks were built using the STRING database and visualized with Cytoscape. Key hub genes and significant gene modules were identified using the Cytoscape plugins CytoHubba and MCODE, followed by further functional analysis of these modules. Results: NGS analysis revealed distinct gene expression profiles in response to single infection with Nb or HSV-2, with both showing significant differences when uninfected controls were compared to infected FGT tissues at a 5% false discovery rate. Notably, there were no significant differences in gene expression profiles between uninfected and co-infected FGT tissues. In the comparison of uninfected versus Nb-infected FGT tissues, 368 DEGs were identified, with 356 genes upregulated and 12 downregulated. Several immune-related genes, such as Ptprc, Ccl11, Ccr2, and Cx3cr1, were significantly altered. Pathway analysis of DEGs, hub genes, and significant modules indicated modulation of immune and defense responses. Notably, Nb infection induced a robust Th2-dominant immune response in the FGT, with downregulation of pro-inflammatory genes. This likely reflects helminth-driven modulation that may impair protective Th1 responses and highlights the systemic impact of Nb on the FGT immunity. In the comparison of uninfected versus HSV-2-infected FGT tissues, 140 DEGs were identified, with 121 upregulated and 19 downregulated. Immune-related genes, including Ldlr, Camk1d, Lrp8 and Epg5, were notably altered. HSV-2 infection led to early and predominant downregulation of immune genes, consistent with viral immune evasion strategies. In addition, functional analysis revealed enrichment in cell cycle and sterol biosynthesis pathways, suggesting that HSV-2 modulates host metabolism to support viral replication while influencing immune responses. In co-infection, no significant transcriptional changes were observed, potentially reflecting immune antagonism where Nb-induced Th2 responses may suppress HSV-2-driven Th1 immune responses. Conclusions: This preliminary study offers insights into the gene expression responses in the FGT to acute single and co-infection with Nb and HSV-2. Together, these findings reveal distinct transcriptomic changes in the FGT following Nb and HSV-2 infection, with co-infection potentially leading to immune antagonism and transcriptional equilibrium. This highlights the complex interplay between helminth- and virus-induced immune modulation in shaping FGT immunity. By leveraging NGS, this study highlights important immune-related pathways and serves as a foundation for further investigations into the mechanistic roles of DEGs in immunity to these pathogens, with potential implications for developing novel therapeutic strategies. Full article

Mouse models serve as a means of examining immune changes when genes of interest are knocked out (KO). One group of immune gene-producing cells that have been identified is type 2 innate lymphoid cells (Ilc2). These cells are involved in the production of Th2 equivalent immune responses and signal cytokine production during the resolution of Nippostrongylus brasiliensis parasite infection in mice lungs. However, many questions about Ilc2 activity in the gut remain. To study this, retinoic acid receptor (RAR)-related orphan receptor alpha (RORα)-deficient mice were infected with adult N. brasiliensis and arranged into four treatment groups. Ten days post-infection (dpi), mouse ileum tissue was extracted for RNA-Seq. The RORα-deficient mice showed little change in gene expression at 10 dpi (N = 51) when compared to the WT mice at 10 dpi (N = 915), displaying dysregulation within the mouse gut. Based on the results, the gene expression in the gut of Ilc2-deficient mice denoted that the inability to craft Ilc2 cells left the mice unable to mount classical helminth immune responses involving humoral, mast cell, and antibody Th2-driven reactions. Overall, the results showed the importance of Ilc2 in the gut during N. brasiliensis infections and the effect that the lack of these cells had on immunity. Full article

Alveolar Echinococcosis (AE) is a serious zoonotic disease caused by infection of Echinococcus multilocularis larvae. To survive within the host, E. multilocularis has developed a complex immune evasion mechanism including the inhibition of complement activation. This study focused on a calreticulin secreted by E. multilocularis (EmCRT) and its role in binding ability to human MBL and inhibiting MBL-mannose-mediated lectin pathway of complement activation. Results demonstrated the binding of recombinant EmCRT protein to both external and natural MBL in serum and the subsequent inhibition of MBL-mannose-initiated lectin pathway reflected by the reduced formation of complement intermediate products C3b and C4b. Fragment mapping determined that the MBL binding site was located within the S-domain of EmCRT. Combining with its role in inhibiting C1q-initiated classical complement activation in our previous study, the inhibition of MBL-mannose-initiated lectin pathway identified in this study suggests EmCRT plays an important role in the immune evasion of E. multilocularis alveolar larvae against host complement attack as a survival strategy within human tissue. This study supports the approach of using EmCRT as a good candidate for vaccine and drug development against E. multilocularis infection. Full article