Eicosanoid‐induced calcium signaling mediates cellular immune responses of <i>Tenebrio molitor</i>

Roy, Miltan Chandra; Kim, Yonggyun

doi:10.1111/eea.13037

Cited by 4 publications

(6 citation statements)

References 31 publications

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“…The relative proportions of these hemocytes were different, of which GR and PL were the major cell types. The coleopteran Tenebrio molitor larvae possesses at least four morphological types of hemocytes, most of which (almost 75%) are GR and PL (Roy & Kim, 2021). In the lepidopteran insect S. exigua , five hemocyte types have been found and show similar relative compositions as those of A. sapporensis (Park & Kim, 2012).…”

Section: Discussionmentioning

confidence: 99%

Immune responses of the Asian onion moth, Acrolepiopsis sapporensis, and their genetic factors from RNA‐Seq analysis

Hrithik

Kim

2023

Arch Insect Biochem Physiol

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A nonmodel insect, Acrolepiopsis sapporensis, has been analyzed in immune responses. The total hemocytes in the fifth instar larvae were 2.33 × 106 cells/mL. These hemocytes comprised at least five different types and different relative ratios: 47% granulocytes, 26% plasmatocytes, 11% oenocytoid, 8% prohemocytes, and 5% spherulocytes. Upon bacterial challenge, some of the hemocytes exhibited typical hemocyte‐spreading behaviors, such as focal adhesion, and filopodial and lamellipodial cytoplasmic extensions. The hemocyte behaviors induced cellular immune responses demonstrated by nodule formation. In addition, the plasma collected from the immune‐challenged larvae exhibited humoral immune responses by bacterial growth inhibition along with enhanced phenoloxidase enzyme activity. These cellular and humoral immune responses were further analyzed by determining the immune‐associated genes from a transcriptome generated by RNA‐Seq. A total of about 12 Gb sequences led to about 218,116 contigs, which were predicted to encode about 46,808 genes. Comparative expression analysis showed 8392 uniquely expressed genes in the immune‐challenged larvae. Differentially expressed gene (DEG) analysis among the commonly expressed genes indicated that 782 genes were upregulated and 548 genes were downregulated in the expressions after bacterial challenge. These immune‐associated genes included pattern recognition receptors, immune mediation/signaling genes, and various immune effectors. Specifically, the genetic components of the Toll, IMD, and JAK/STAT immune signaling pathways were included in the DEG database. These results demonstrate the immune responses of A. sapporensis larvae and suggest the genes associated with the immune responses in this nonmodel insect.

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Section: Discussionmentioning

confidence: 99%

Immune responses of the Asian onion moth, Acrolepiopsis sapporensis, and their genetic factors from RNA‐Seq analysis

Hrithik

Kim

2023

Arch Insect Biochem Physiol

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“…, 2018), activates hemocytes, phagocytosis, and the proPO system (Mandato et al. , 1997; Roy & Kim, 2021). In particular, PGE 2 can mediate the occurrence of apoptosis in G. mellonella hemocytes (Wrońska et al.…”

Section: Discussionmentioning

confidence: 99%

Morphofunctional characterization of hemocytes in black soldier fly larvae

et al. 2022

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In insects, the cell-mediated immune response involves an active role of hemocytes in phagocytosis, nodulation, and encapsulation. Although these processes have been well documented in multiple species belonging to different insect orders, information concerning the immune response, particularly the hemocyte types and their specific function in the black soldier fly Hermetia illucens, is still limited. This is a serious gap in knowledge given the high economic relevance of H. illucens larvae in waste management strategies and considering that the saprophagous feeding habits of this dipteran species have likely shaped its immune system to efficiently respond to infections. The present study represents the first detailed characterization of black soldier fly hemocytes and provides new insights into the cell-mediated immune response of this insect. In particular, in addition to prohemocytes, we identified five hemocyte types that mount the immune response in the larva, and analyzed their behavior, role, and morphofunctional changes in response to bacterial infection and injection of chromatographic beads. Our results demonstrate that the circulating phagocytes in black soldier fly larvae are plasmatocytes. These cells also take part in nodulation and encapsulation with granulocytes and lamellocyte-like cells, developing a starting core for nodule/capsule formation to remove/encapsulate large bacterial aggregates/pathogens from the hemolymph, respectively. These processes are supported by the release of melanin precursors from crystal cells and likely by mobilizing nutrient reserves in newly circulating adipohemocytes, which could thus trophically support other hemocytes during the immune response. Finally, the regulation of the cell-mediated immune response by eicosanoids was investigated.

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“…One eicosanoid action in insect cellular immunity is the activation of Ca 2+ signaling within hemocytes in mealworms, Tenebrio molitor. Roy and Kim (33) reported that bacterial infections stimulate Ca 2+ activation, recorded as Fura-positive cells. One role of Ca 2+ is activating hemocyte spread by F-actin extension, documented by co-localization of Ca 2+ and F-actin.…”

Section: Discussionmentioning

confidence: 99%

“…To observe the Ca 2+ signal and hemocyte aggregation behavior in response to fungal challenges (33), L5 larvae of S. exigua were injected with 2 µL Fura-8 (1 mM) and incubated for 30 min. 2 µL of fungal conidia and hyphae were injected.…”

Section: Ca 2+ Signaling In Response To Fungal Challengementioning

confidence: 99%

Thromboxane Mobilizes Insect Blood Cells to Infection Foci

et al. 2021

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Innate immune responses are effective for insect survival to defend against entomopathogens including a fungal pathogen, Metarhizium rileyi, that infects a lepidopteran Spodoptera exigua. In particular, the fungal virulence was attenuated by cellular immune responses, in which the conidia were phagocytosed by hemocytes (insect blood cells) and hyphal growth was inhibited by hemocyte encapsulation. However, the chemokine signal to drive hemocytes to the infection foci was little understood. The hemocyte behaviors appeared to be guided by a Ca2+ signal stimulating cell aggregation to the infection foci. The induction of the Ca2+ signal was significantly inhibited by the cyclooxygenase (COX) inhibitor. Under the inhibitory condition, the addition of thromboxane A2 or B2 (TXA2 or TXB2) among COX products was the most effective to recover the Ca2+ signal and hemocyte aggregation. TXB2 alone induced a microaggregation behavior of hemocytes under in vitro conditions. Indeed, TXB2 titer was significantly increased in the plasma of the infected larvae. The elevated TXB2 level was further supported by the induction of phospholipase A2 (PLA2) activity in the hemocytes and subsequent up-regulation of COX-like peroxinectins (SePOX-F and SePOX-H) in response to the fungal infection. Finally, the expression of a thromboxane synthase (Se-TXAS) gene was highly expressed in the hemocytes. RNA interference (RNAi) of Se-TXAS expression inhibited the Ca2+ signal and hemocyte aggregation around fungal hyphae, which were rescued by the addition of TXB2. Without any ortholog to mammalian thromboxane receptors, a prostaglandin receptor was essential to mediate TXB2 signal to elevate the Ca2+ signal and mediate hemocyte aggregation behavior. Specific inhibitor assays suggest that the downstream signal after binding TXB2 to the receptor follows the Ca2+-induced Ca2+ release pathway from the endoplasmic reticulum of the hemocytes. These results suggest that hemocyte aggregation induced by the fungal infection is triggered by TXB2via a Ca2+ signal through a PG receptor.

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Eicosanoid‐induced calcium signaling mediates cellular immune responses of Tenebrio molitor

Cited by 4 publications

References 31 publications

Immune responses of the Asian onion moth, Acrolepiopsis sapporensis, and their genetic factors from RNA‐Seq analysis

Immune responses of the Asian onion moth, Acrolepiopsis sapporensis, and their genetic factors from RNA‐Seq analysis

Morphofunctional characterization of hemocytes in black soldier fly larvae

Thromboxane Mobilizes Insect Blood Cells to Infection Foci

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