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Khan SA, Kojour MAM, Han YS. Recent trends in insect gut immunity. Front Immunol 2023; 14:1272143. [PMID: 38193088 PMCID: PMC10773798 DOI: 10.3389/fimmu.2023.1272143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 11/29/2023] [Indexed: 01/10/2024] Open
Abstract
The gut is a crucial organ in insect defense against various pathogens and harmful substances in their environment and diet. Distinct insect gut compartments possess unique functionalities contributing to their physiological processes, including immunity. The insect gut's cellular composition is vital for cellular and humoral immunity. The peritrophic membrane, mucus layer, lumen, microvilli, and various gut cells provide essential support for activating and regulating immune defense mechanisms. These components also secrete molecules and enzymes that are imperative in physiological activities. Additionally, the gut microbiota initiates various signaling pathways and produces vitamins and minerals that help maintain gut homeostasis. Distinct immune signaling pathways are activated within the gut when insects ingest pathogens or hazardous materials. The pathway induced depends on the infection or pathogen type; include immune deficiency (imd), Toll, JAK/STAT, Duox-ROS, and JNK/FOXO regulatory pathways. These pathways produce different antimicrobial peptides (AMPs) and maintain gut homeostasis. Furthermore, various signaling mechanisms within gut cells regulate insect gut recovery following infection. Although some questions regarding insect gut immunity in different species require additional study, this review provides insights into the insect gut's structure and composition, commensal microorganism roles in Drosophila melanogaster and Tenebrio molitor life cycles, different signaling pathways involved in gut immune systems, and the insect gut post-infection recovery through various signaling mechanisms.
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Affiliation(s)
- Shahidul Ahmed Khan
- Department of Applied Biology, Institute of Environmentally Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju, Republic of Korea
| | - Maryam Ali Mohmmadie Kojour
- Life & Medical Sciences Institute (LIMES) Development, Genetics & Molecular Physiology Unit, University of Bonn, Bonn, Germany
| | - Yeon Soo Han
- Department of Applied Biology, Institute of Environmentally Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju, Republic of Korea
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Ko HJ, Jang HA, Park KB, Kim CE, Patnaik BB, Lee YS, Han YS, Jo YH. IKKβ regulates antimicrobial innate immune responses in the yellow mealworm, Tenebrio molitor. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 147:104761. [PMID: 37331676 DOI: 10.1016/j.dci.2023.104761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 06/20/2023]
Abstract
Toll and IMD pathways regulate antimicrobial innate immune responses in insect model systems. The transcriptional activation of antimicrobial peptides (AMPs) confers humoral immunity in the host against invaded pathogens. The IKK kinase complex (IKKα, IKKβ, and the regulatory subunit IKKγ/NEMO) centrally regulates the NF-κB response to various stimuli. It triggers an appropriate antimicrobial immune response in the host. In this study, a TmIKKβ (or TmIrd5) homolog was screened from the RNA-seq database of the coleopteran beetle, Tenebrio molitor. A single exon characterizes the TmIKKβ gene, and the open reading frame (ORF) comprises of 2112 bp that putatively encodes a polypeptide of 703 amino acid residues. TmIKKβ contains a serine/threonine kinase domain and is phylogenetically close to Tribolium castaneum IKKβ homolog (TcIKKβ). TmIKKβ transcripts were highly expressed in the early pupal (P1) and adult (A5) stages. Among the tissues, TmIKKβ showed higher expression in the integument of the last instar larvae and the fat body and hemocytes of 5-day-old adults. TmIKKβ mRNA was upregulated post-E. coli challenge to the host. Moreover, RNAi-based TmIKKβ mRNA silencing increased host larvae' susceptibility against E. coli, S. aureus and C. albicans. TmIKKβ RNAi in the fat body led to a downregulation in mRNA expression of ten out of fourteen AMP genes, including TmTenecin1, -2, and -4; TmDefensin, and -like; TmColeoptericinA, and -B; and TmAttacin1a, -1b, and -2, suggesting the requirement of the gene in antimicrobial innate immune responses. Further, a decrease in the mRNA expression of NF-κB factors such as TmRelish, TmDorsal1, and TmDorsal2 in the fat body of T. molitor larvae was observed post-microorganisms challenge. Thus, TmIKKβ regulates antimicrobial innate immune responses in T. molitor.
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Affiliation(s)
- Hye Jin Ko
- Division of Plant Biotechnology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Ho Am Jang
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan City, 31538, Republic of Korea
| | - Ki Beom Park
- Division of Plant Biotechnology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Chang Eun Kim
- Division of Plant Biotechnology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Bharat Bhusan Patnaik
- Korea Native Animal Resources Utilization Convergence Research Institute (KNAR), Soonchunhyang University, Asan, Chungnam, South Korea; P.G Department of Biosciences and Biotechnology, Fakir Mohan University, Nuapadhi, Balasore, Odisha, 756089, India
| | - Yong Seok Lee
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan City, 31538, Republic of Korea; Korea Native Animal Resources Utilization Convergence Research Institute (KNAR), Soonchunhyang University, Asan, Chungnam, South Korea
| | - Yeon Soo Han
- Division of Plant Biotechnology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Yong Hun Jo
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan City, 31538, Republic of Korea.
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Ali Mohammadie Kojour M, Jang HA, Lee YS, Jo YH, Han YS. Innate Immune Response of TmToll-3 Following Systemic Microbial Infection in Tenebrio molitor. Int J Mol Sci 2023; 24:ijms24076751. [PMID: 37047723 PMCID: PMC10095136 DOI: 10.3390/ijms24076751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/08/2023] Open
Abstract
Although Toll-like receptors have been widely identified and functionally characterized in mammalian models and Drosophila, the immunological function of these receptors in other insects remains unclear. Here, we explored the relevant innate immune response of Tenebrio molitor (T. molitor) Toll-3 against Gram-negative bacteria, Gram-positive bacteria, and fungal infections. Our findings indicated that TmToll-3 expression was mainly induced by Candida albicans infections in the fat bodies, gut, Malpighian tubules, and hemolymph of young T. molitor larvae. Surprisingly, Escherichia coli systemic infection caused mortality after TmToll-3 knockdown via RNA interference (RNAi) injection, which was not observed in the control group. Further analyses indicated that in the absence of TmToll-3, the final effector of the Toll signaling pathway, antimicrobial peptide (AMP) genes and relevant transcription factors were significantly downregulated after E. coli challenge. Our results indicated that the expression of almost all AMP genes was suppressed in silenced individuals, whereas the expression of relevant genes was positively regulated after fungal injection. Therefore, this study revealed the immunological involvement of TmToll-3 in T. molitor in response to systematic infections.
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Affiliation(s)
- Maryam Ali Mohammadie Kojour
- Department of Applied Biology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Ho Am Jang
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan 31538, Republic of Korea
| | - Yong Seok Lee
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan 31538, Republic of Korea
| | - Yong Hun Jo
- Department of Biology, College of Natural Sciences, Soonchunhyang University, Asan 31538, Republic of Korea
| | - Yeon Soo Han
- Department of Applied Biology, Institute of Environmentally-Friendly Agriculture (IEFA), College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
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