Reactive oxygen species (ROS) are integral to antimicrobial defense but must be tightly regulated to prevent oxidative damage and dysregulated immune responses. Peroxiredoxin 1 (Prdx1), a conserved thiol-dependent peroxidase, has been implicated in host defense and inflammatory regulation in teleosts; however, how the intracellular redox-regulatory function of teleost Prdx1 relates to macrophage responses during bacterial challenge remains insufficiently defined. To address this question, we characterized zebrafish Prdx1 (DrPrdx1) at the molecular and biochemical levels and examined its relationship with intracellular ROS and macrophage responses to Aeromonas hydrophila. Phylogenetic and sequence analyses revealed evolutionary conservation of DrPrdx1, including preservation of catalytic cysteine residues essential for peroxide reduction. Drprdx1 was broadly expressed across zebrafish tissues and showed tissue- and time-dependent transcriptional responses to bacterial challenge. Recombinant DrPrdx1 exhibited H2O2-scavenging activity and protected plasmid DNA from oxidative damage in vitro. In RAW264.7 macrophages stably expressing zebrafish Prdx1, infection-induced intracellular superoxide accumulation was attenuated, and the proportion of macrophages engaging in bacterial internalization was increased. Transcriptional analyses further revealed selective and time-dependent changes in inflammatory and apoptosis-related gene expression during early bacterial challenge. Collectively, these findings support a model in which DrPrdx1-associated redox modulation may contribute to the regulation of macrophage responses during bacterial challenge, providing insight into potential redox-regulatory mechanisms in teleost innate immunity.
Glutaredoxins (Grxs) are crucial components of the cellular antioxidant defense system, maintaining redox homeostasis and protecting against oxidative stress. In this study, the glutaredoxin 1 gene from Scomber japonicus ( Sjgrx1 ) was functionally characterized. The open reading frame of Sjgrx1 encodes a protein of 106 amino acids with conserved features, including a CXXC motif and glutathione binding sites. Under normal conditions, Sjgrx1 expression was predominantly detected in peripheral blood cells (PBCs), gills, and liver. Moreover, it was significantly upregulated in PBCs, trunk-kidney, and spleen during immune challenges with polyinosinic:polycytidylic acid (poly I:C), lipopolysaccharide (LPS), and Vibrio harveyi (VH). Recombinant Sjgrx1 protein (rSjgrx1) demonstrated significant disulfide-reducing ability and reactive oxygen species scavenging capacity. Sjgrx1 overexpression in fathead minnow (FHM) cells enhanced cell viability, reduced apoptosis under oxidative stress, and significantly promoted wound healing. Moreover, Sjgrx1 overexpression in RAW264.7 cells decreased LPS-induced nitric oxide production and induced the M2-like phenotype change at basal condition. Collectively, our findings provide the first comprehensive characterization of Sjgrx1 in S. japonicus , demonstrating its inducible expression following immune stimulation, antioxidant activity, cytoprotective effects against oxidative stress, and immunomodulatory potential.
The interleukin (IL)-17 family consists of pro-inflammatory cytokines involved in mucosal immunity and host defense against infections. IL-17A/F homologs (IL-17A/F1–3) have been identified in teleosts, but their functional diversity and receptor-mediated signaling remain poorly understood. We previously characterized IL-17 receptor homologs il17rca and il17rcb in Japanese medaka (Oryzias latipes) and identified two splice variants of il17rca (il17rca1 and il17rca2). However, whether these receptor isoforms differentially regulate immune responses remains to be clarified. Thus, this study aimed to elucidate the functional interactions between IL-17A/F ligands and IL-17RC isoforms. Medaka il17rca1, il17rca2, and il17rcb were overexpressed in OLHNI-2 cells and then stimulated with recombinant IL-17A/F1–3 proteins. Overexpression of il17rca1 significantly induced the expression of il1b and s100a1 in response to IL-17A/F1, whereas IL-17A/F2 upregulated the expression of s100t, s100a1, and defb. By contrast, IL-17A/F3 and il17rcb exerted minimal effects on gene induction. Notably, co-expression of il17rca2 suppressed il17rca1-mediated gene expression, suggesting a negative regulatory effect of IL-17RCa2 under these experimental conditions. These findings demonstrate functional divergence among IL-17A/F ligands and reveal that IL-17RC isoforms differentially regulate IL-17 signaling, providing new insights into the complexity of teleost immune regulation.
White spot syndrome virus (WSSV) is a highly virulent pathogen affecting the shrimp Litopenaeus vannamei . WSSV infection induces early molecular changes in host tissues, including structural, metabolic, and immune-related pathways. Several shrimp proteins identified as allergen-associated proteins in crustaceans including tropomyosin (TM), arginine kinase (AK), myosin light chain (MLC), sarcoplasmic calcium-binding protein (SCBP), and hemocyanin, participate in essential cellular and immune functions but they are also recognized as allergens in humans. This study evaluated the effect of WSSV infection on the expression of allergen-associated genes in muscle and hemocytes of L. vannamei . Adult shrimp received 20 μL of WSSV inoculum or sterile 0.7% saline solution and were sampled from 1 to 72 h post-infection (hpi). Viral infection was assessed by qPCR targeting Ie 1–126. WSSV-infected shrimp showed clinical signs at 12–18 hpi. Relative gene expression analysis revealed tissue-specific modulation; in muscle, TM, AK, and MLC were significantly upregulated at late stages of infection (48–72 hpi), whereas in hemocytes, hemocyanin was the only gene significantly upregulated. Complementary ileal histopathological observations were performed in Wistar rats fed with crude extracts of non-infected or WSSV-infected shrimp tissues. Intestinal structural alterations and inflammatory cell infiltration, including eosinophil and mast cell recruitment, were more evident tissue alterations in rats exposed to extracts obtained from WSSV-infected shrimp. The upregulation of genes encoding allergenic proteins in shrimps in response to viral infection is a topic that deserves further investigation, considering the worldwide distribution of the virus.
