Transglutaminase Research Articles

Synergistic recovery and enhancement of gelling properties of oxidatively damaged myofibrillar protein by l-lysine and transglutaminase

The influence of combined Lysine (Lys) and transglutaminase (TG) on the conformation and gelling properties of oxidatively damaged myofibrillar protein (MP) was investigated. The addition of Lys (5 mM) significantly increased the α-helix content (by 47.8%) and decreased the particle size of oxidatively damaged MP, and improved the cooking yield (by 16.8%) and the breaking strength of MP gels (by 65.5%). The treatment with TG (E:S = 1:500) led to a slightly reduced α-helix content but improved breaking strength (by 41.8%) and cooking loss (by 13.3%) of the gels. Their combination (Lys + TG) showed the greatest and synergistic overall improvement, with the set gel displaying a fine, smooth and compact network structure. Notably, the gelling ability of oxidatively damaged MP upon Lys + TG treatment was significantly stronger than that of non-oxidized MP far exceeding its recovery. Therefore, significantly enhanced gelling properties of oxidatively damaged MP can be attained through the combination Lys and TG.

Grainyhead-like transcription factors: guardians of the skin barrier.

There has been selective pressure to maintain a skin barrier since terrestrial animals evolved 360 million years ago. These animals acquired an unique integumentary system with a keratinized, stratified, squamous epithelium surface barrier. The barrier protects against dehydration and entry of microbes and toxins. The skin barrier centres on the stratum corneum layer of the epidermis and consists of cornified envelopes cemented by the intercorneocyte lipid matrix. Multiple components of the barrier undergo cross-linking by transglutaminase (TGM) enzymes, while keratins provide additional mechanical strength. Cellular tight junctions also are crucial for barrier integrity. The grainyhead-like (GRHL) transcription factors regulate the formation and maintenance of the integument in diverse species. GRHL3 is essential for formation of the skin barrier during embryonic development, whereas GRHL1 maintains the skin barrier postnatally. This is achieved by transactivation of Tgm1 and Tgm5, respectively. In addition to its barrier function, GRHL3 plays key roles in wound repair and as an epidermal tumour suppressor. In its former role, GRHL3 activates the planar cell polarity signalling pathway to mediate wound healing by providing directional migration cues. In squamous epithelium, GRHL3 regulates the balance between proliferation and differentiation, and its loss induces squamous cell carcinoma (SCC). In the skin, this is mediated through increased expression of MIR21, which reduces the expression levels of GRHL3 and its direct target, PTEN, leading to activation of the PI3K-AKT signalling pathway. These data position the GRHL family as master regulators of epidermal homeostasis across a vast gulf of evolutionary history.

Enzyme Catalyzed Hydrogel as Versatile Bioadhesive for Tissue Wound Hemostasis, Bonding, and Continuous Repair.

Developing a versatile bioadhesive which is biocompatible, adhesive, hemostatic, and therapeutic is of great significance to promote wound sealing and healing. Herein, an adhesive (GTT-3 hydrogel) is fabricated by catalysis of tannic acid modified gelatin (Gel-TA) with transglutaminase (TG). The hydrogen bonding, imine linking, and acyl-transfer reaction between GTT-3 hydrogel and tissue enable efficient hydrogel integration and adhesion to tissue instantly, so as to seal the wound and stop bleeding. Moreover, the intrinsic wound healing ability of gelatin and the antibacterial properties of TA provide favorable conditions for wound healing after adhesion. In vitro mechanical property testing and cell experimental results determine the elasticity, adhesion, and biocompatibility of the GTT-3 hydrogel. The wound operation in mouse models and pathological sectioning results indicate that GTT-3 adhesive obviously accelerates hemostasis, wound bonding, and healing. With the special property of instant adhesion and excellent hemostatic and therapeutic repair effects, GTT-3 hydrogel may provide a new option for surgical operation.

Low-Temperature Argon Plasma Regulates Skin Moisturizing and Melanogenesis-Regulating Markers through Yes-Associated Protein.

Extensive water loss and melanin hyperproduction can cause various skin disorders. Low-temperature argon plasma (LTAP) has shown the possibility of being used for the treatment of various skin diseases, such as atopic dermatitis and skin cancer. However, the role of LTAP in regulating skin moisturizing and melanogenesis has not been investigated. In this study, we aimed to determine the effect of LTAP on yes-associated protein (YAP), a major transcriptional coactivator in the Hippo signaling pathway that is involved in skin moisturizing and melanogenesis-regulating markers. In normal human epidermal keratinocytes (NHEKs), the human epidermal keratinocyte line HaCaT, and human dermal fibroblasts (HDFs), we found that LTAP exhibited increased expression levels of YAP protein. In addition, the expression levels of filaggrin (FLG), which is involved in natural moisturizing factors (NMFs), and hyaluronic acid synthase (HAS), transglutaminase (TGM), and involucrin (IVL), which regulate skin barrier and moisturizing, were also increased after exposure to LTAP. Furthermore, collagen type I alpha 1 and type III alpha 1 (COL1A1, COL3A1) were increased after LTAP exposure, but the expression level of matrix metalloproteinase-3 (MMP-3) was reduced. Moreover, LTAP was found to suppress alpha-melanocyte stimulating hormone (α-MSH)-induced melanogenesis in murine melanoma B16F10 cells and normal human melanocytes (NHEMs). LTAP regulates melanogenesis of the melanocytes through decreased YAP pathway activation in a melanocortin 1 receptor (MC1R)-dependent manner. Taken together, our data show that LTAP regulates skin moisturizing and melanogenesis through modulation of the YAP pathway, and the effect of LTAP on the expression level of YAP varies from cell to cell. Thus, LTAP might be developed as a treatment method to improve the skin barrier, moisture content, and wrinkle formation, and to reduce melanin generation.

Nickel ions attenuate autophagy flux and induce transglutaminase 2 (TG2) mediated post-translational modification of SQSTM1/p62

Nickel, the most frequent contact allergy cause, is widely used for various metallic materials and medical devices. Autophagy is an intracellular protein degradation system and contributes to metal recycling. However, it is unclear the functions of nickel in autophagy. We here demonstrated that NiCl2 induced microtubule-associated protein 1 light chain 3 (LC3)-II and LC3 puncta, markers of autophagosomes. Bafilomycin A1 (BafA1) treatment did not enhance LC3 puncta under NiCl2 stimulation, suggesting that NiCl2 did not induce autophagic flux. In addition, NiCl2 promotes the accumulation of SQSTM1/p62 and increased SQSTM1/p62 colocalization with lysosomal-associated membrane protein 1 (LAMP1). These data indicated that NiCl2 attenuates autophagic flux. Interestingly, NiCl2 induced the expression of the high-molecular-weight (MW) form of SQSTM1/p62. Inhibition of NiCl2-induced reactive oxygen species (ROS) reduced the high-MW SQSTM1/p62. We also showed that NiCl2-induced ROS activate transglutaminase (TG) activity. We found that transglutaminase 2 (TG2) inhibition reduced high-MW SQSTM1/p62 and SQSTM1/p62 puncta under NiCl2 stimulation, indicating that TG2 regulates SQSTM1/p62 protein homeostasis under NiCl2 stimulation. Our study demonstrated that nickel ion regulates autophagy flux and TG2 restricted nickel-dependent proteostasis.

Gel properties of transglutaminase-induced soy protein isolate-polyphenol complex: influence of epigallocatechin-3-gallate.

Traditional soy protein isolate (SPI)-based gel products, such as tofu, are generally produced by heating and by addition of metal salt ions to adjust the hydrophobicity and electrostatic force of soybean protein to facilitate the formation of a uniform network structure. However, the gelation rate of the soy protein gel network structure is difficult to control. Theoretically, epigallocatechin-3-gallate (EGCG) could be used to alter the surface hydrophobicity of thermally induced SPI to improve its gelation rate and form a more uniform network structure, thus improving SPI-based gel properties (hardness, water holding capacity and rheological properties). An SPI-EGCG complex (SPIE) was prepared, and properties of the resulting gel, following induction of transglutaminase (TG), were evaluated. Results showed that EGCG is bound to thermally induced SPI primarily via hydrophobic and hydrogen bonding, thus altering the secondary structure composition and reducing surface hydrophobicity of proteins in thermally induced SPI. Furthermore, the optimum amount of EGCG required to improve the gel strength, water holding capacity and rheological properties was ≤0.04:1 (SPI 1 g L-1 ; EGCG:SPI, w/w). Thermal stability analysis further indicated that EGCG in SPIE was more stable than free EGCG after heating. This study demonstrated that EGCG can improve the gel properties of TG-crosslinked SPIE, while EGCG in SPIE exhibits enhanced thermal stability. Additionally, the results of this study provide a novel strategy for the development of SPI-based gel foods with improved gel properties and that are enriched with bioactive compounds. © 2020 Society of Chemical Industry.

Production of transglutaminase in glutathione-producing recombinant Saccharomyces cerevisiae

Transglutaminase (TG) catalyzes the formation of cross-links between proteins. TG from Streptoverticillium mobaraense (SmTG) is used widely in food, cosmetic, biomaterial and medical industries. SmTG is occasionally supplied as a mixture with the activator peptide glutathione. Currently, glutathione is industrially produced using a budding yeast, Saccharomyces cerevisiae, because of its intracellular high content of glutathione. In this study, active SmTG was produced together with glutathione in S. cerevisiae. SmTG extracted from S. cerevisiae expressing SmTG showed cross-linking activity when BSA and sodium caseinate were substrates. The cross-linking activity of SmTG increased proportionally as the concentration of added glutathione increased. Furthermore, SmTG was prepared by extracting SmTG from an engineered S. cerevisiae whose glutathione synthetic pathway was enhanced. The SmTG solution showed higher activity when compared with a SmTG solution prepared from a S. cerevisiae strain without enhanced glutathione production. This result indicates that a high content of intracellular glutathione further enhances active SmTG production in S. cerevisiae. S. cerevisiae co-producing SmTG and a higher content of glutathione has the potential to supply a ready-to-use industrial active TG solution.

Preparation of high thermal stability gelatin emulsion and its application in 3D printing

In this study, the gelatin crosslinked by Transglutaminase (TG) was applied to stabilize food-grade high internal phase emulsions (HIPEs) by a facile one-step method. The influence of TG crosslinking time on the molecular weight distribution of gelatin and the microstructure, thermal stability and rheological properties of the HIPEs were investigated. The results showed that TG crosslinking effectively promoted the production of high weight molecular. The obtained HIPEs exhibited a uniform droplet diameter and a good storage stability. An excellent thermal stability was achieved among the HIPEs stabilized by TG-crosslinked gelatin. After heating at 90 °C and 121 °C for 20 min, there was little change in microstructure and viscosity when the crosslinking time reached 4 h, implying that it could be stored at room temperature through high temperature sterilization. In the rheological analysis, the HIPEs showed a higher viscosity and lower frequency dependence with the extension of the crosslinking time, suggesting its potential application in three dimensional (3D) printing. The subsequent 3D printing experiments also confirmed that the HIPEs had a good printing performance, and some 3D printing models with different colors could be successfully obtained. This study provides a facile industrialized method for gelatin-based HIPEs with high thermal stability, and supplies theoretical guidance for its practical application.

Enhancement of skin barrier and hydration-related molecules by protopanaxatriol in human keratinocytes

BackgroundProtopanaxatriol (PPT) is a secondary intestinal metabolite of ginsenoside in ginseng. Although the effects of PPT have been reported in various diseases including cancer, diabetes and inflammatory diseases, the skin protective effects of PPT are poorly understood. MethodsHaCaT cells were treated with PPT in a dose-dependent manner. mRNA and protein levels which related to skin barrier and hydration were detected compared with retinol. Luciferase assay was performed to explore the relative signaling pathway. Western blot was conducted to confirm these pathways and excavated further signals. ResultsPPT enhanced the expression of filaggrin (FLG), transglutaminase (TGM)-1, claudin, occludin and hyaluronic acid synthase (HAS) −1, −2 and −3. The mRNA expression levels of FLG, TGM-1, HAS-1 and HAS-2 were suppressed under NF-κB inhibition. PPT significantly augmented NF-κB-luc activity and upregulated Src/AKT/NF-κB signaling. In addition, PPT also increased phosphorylation of the mitogen-activated protein kinases (MAPKs) ERK, JNK and p38 and upstream MAPK activators (MEK and MKK). Furthermore, transcriptional activity of AP-1 and CREB, which are downstream signaling targets of MAPK, was enhanced by PPT. ConclusionPPT improves skin barrier function and hydration through Src/AKT/NF-κB and MAPK signaling. Therefore, PPT may be a valuable component for cosmetics or treating skin disorders.

Long-Standing Ulcerative Colitis and Sulphasalazine Treatment Complicated by Adult Celiac Disease

The risk of celiac disease may be increased in patients with inflammatory bowel disease (IBD), however, the precise pathogenetic mechanisms involved remain controversial. In this report, an elderly man with long-standing and extensive ulcerative colitis was treated with daily salazopyrine for over 30 years. His medication was eventually discontinued although endoscopic surveillance studies showed healed colitis with minimal inflammatory change and no dysplasia. He subsequently volunteered as an IBD control in a celiac disease research study. Endomysial and tissue transglutaminase antibodies were unexpectedly positive and a small bowel biopsy showed changes of celiac disease that later responded to a gluten-free diet. Earlier historical duodenal and ileal biopsies had been normal suggesting that changes were new, developing after cessation of the salazopyrine. This unusual presentation “unmasking” celiac disease after cessation of long-standing salazopyrine for colitis raises the potential that the drug may have acted to suppress the inflammatory process in celiac disease and may offer another alternate and inexpensive therapeutic approach.

Design and characterization of double-cross-linked emulsion gels using mixed biopolymers: Zein and sodium alginate

In this study, a double-cross-linked emulsion gel was formed using a Pickering emulsion as a template and two food-grade biopolymers, zein and sodium alginate (SA), as gelling agents. First, the zein was crosslinked with transglutaminase (TG) and then the alginate was crosslinked with calcium ions. The structure, interactions, and functional properties of the composite systems were then characterized using microscopy, infrared spectroscopy, and rheology measurements. These methods provided valuable insights into the formation mechanism of the double-cross-linked emulsion gels. The effects of single/double cross-linked emulsion gels on the photostability and bioaccessibility of co-loaded polyphenols (curcumin and resveratrol) were also compared. Our results show that SA concentration and TG activity impact emulsion gels stability and rheology. Single-cross-linked emulsion gels could be formed by only crosslinking SA (0.5 wt%) with calcium ions, but not by only crosslinking zein with TG. Double-cross-linked emulsion gels with dense network microstructures and high viscoelasticity were formed by using 60 U/g TG and 1.25 mM Ca2+ to crosslink the protein and polysaccharide, respectively. The single cross-linked emulsion gels improved the light stability and bioaccessibility of the two polyphenols, with the Ca2+-crosslinked system being more effective than the TG-crosslinked one. The double-cross-linked emulsion gels gave higher light stability and bioaccessibility than the single-cross-linked ones. Overall, this study shows that using a combination of TG and Ca2+ to crosslink the two biopolymers leads to edible composite materials with improved functional performance.

The characteristics of gelation of myofibrillar proteins combined with salt soluble Rhodotorula glutinis proteins by enzymatic crosslinking

Some microbial single-cell proteins are capable of producing synergistic crosslinking interactions with edible proteins by rational regulation. Herein, we reported that salt soluble proteins (RGP) extracted from Rhodotorula glutinis in an alkaline and saline system may combine with myofibrillar proteins (MP) by transglutaminase (TG) polymerization to form improvable irreversible thermal co-gels. The combination of MP, RGP, and TG, namely restructured MP gels, led to significantly enhanced water holding capacity (WHC), up to 90.76 ± 1.88% (% of retained water) and textural properties (hardness, springiness, and adhesiveness) as well as decreases of ‘gauche-gauche-gauche’ SS bonds and α-helix conformations and increases of ‘gauche-gauche-trans’ SS bonds and β-fold conformations, compared to MP and MP-RGP groups. Differential scanning calorimetry analysis validated that thermostability of myosins and actins from MP was reduced after using RGP, TG, and their combination, and unfolding and denaturation of myosin occurred easily during thermal co-gelation by TG and/or RGP.

Preparation and characterization of gelatin films by transglutaminase cross-linking combined with ethanol precipitation or Hofmeister effect

In this study, the gelatin films were prepared by dehydration with ethanol precipitation or Hofmeister effect via absolute ethanol or saturated (NH4)2SO4 solution after transglutaminase (TG) cross-linking. The prepared gelatin films remained the integrity after heat treatments (boiling or high-temperature sterilization), and had a low water vapor permeability (WVP) due to TG cross-linking. Ethanol precipitation improved the mechanical, water barrier (water solubility) and visual sensory (color difference and transparency) properties of the gelatin films especially at a high gelatin concentration, which was due to the increase of hydrogen bonding and triple helix content, and ethanol decolorization effect, respectively. The tensile strength (TS) and elongation at break (EAB) were increased by 155.28% and 72.73% than in oven-dried gelatin film (15% gelatin concentration). The results of thermo-gravimetric analysis (TGA) and thermal shrinkage suggested the enhanced thermal stability of films induced by ethanol precipitation due to more orderly internal structure. Although mechanical properties and thermal shrinkage of gelatin films could also be improved by Hofmeister effect, the (NH4)2SO4 migrated to films after dehydration, especially at a low gelatin concentration, which limits the application of this method. The present results indicated that TG cross-linking combined with ethanol precipitation can serve as an effective method to obtain gelatin films with good thermal stability and mechanical, visual sensory and water barrier properties.

Insight into the advantages of premixing yeast-wheat gluten and combining ultrasound and transglutaminase pretreatments in producing umami enzymatic protein hydrolysates

This study aimed to utilize effectively industrial byproducts, yeast suspension (Y) and wheat gluten (W), to produce umami protein hydrolysates as seasonings. Y and W were mixed to yield YW, followed by a pretreatment (ultrasound, transglutaminase (TG), or their combination) and then proteolysis with a yeast extract enzyme and trypsin. Premixing Y and W promoted their dispersibility, and suppressed gluten aggregation and hydrolysate’s bitterness. All pretreatments increased protein recovery. Ultrasound alone or ultrasound with TG increased the embedding of yeasts in W, umami and salty tastes, hydrolysis degree and proportion of molecules < 3 kDa of the YW hydrolysate. For the first time, premixing Y and W, and pretreating YW (by ultrasound then TG-catalyzed protein crosslinking), were found to increase the β-sheet and random coil contents and decreased the β-turn content and surface hydrophobicity, leading to a low-cost umami and non-bitter protein hydrolysate with 56% of species < 1 kDa.

Fabrication and characterization of bi-crosslinking Pickering emulsions stabilized by gliadin/alginate coacervate particles

To develop the interface enhanced emulsion, the Pickering emulsions stabilized by gliadin-sodium alginate (SA) coacervate particles (GSCPs) under crosslinking of transglutaminase (TG) and calcium ion (Ca2+) were investigated. The interaction, microstructure, rheology, texture, physical and oxidation stabilities of bi-crosslinking Pickering emulsions were mainly studied. The non-crosslinking Pickering emulsions stabilized by GSCPs at pH 3.5 had the highest oil encapsulation efficiency (91.8 ± 2.0%), surface loading protein ability (97.4 ± 5.0%) and viscoelasticity. Compared with non-crosslinking emulsions, TG-crosslinking, Ca2+-crosslinking and bi-crosslinking emulsions had varying degrees of positive effects on rheology. Interestingly, the positive effects were more obvious on texture and physical stability. Furthermore, the lower hexanal levels of bi-crosslinking Pickering emulsions suggested that there was a synergic effect between TG and Ca2+ at enhancing emulsion interface strength. This study provides a potential strategy to enhance interfacial architecture and improve the stability of edible Pickering emulsions via crosslinking process.

Transglutaminase release and activity from novel poly(ε-caprolactone)-based composites prepared by foaming with supercritical CO2

In this study, a green approach involving foaming techniques using supercritical CO2 (scCO2) and a salt leaching method was used to prepare new types of poly(ε-caprolactone) (PCL)-based scaffolds with entrapped thermo-sensitive enzyme transglutaminase (TGM). Porous PCL-based composites containing chitosan (CS) and hydroxyapatite (HAp) were characterized using different techniques to measure their composition, mechanical, morphological and sorption properties as a result of CO2 uptake. Scaffolds with improved mechanical properties and high porosity were obtained. The prepared scaffolds were assayed for their protein release patterns and enzymatic activity. When the enzyme was crosslinked into chitosan matrices with glutaraldehyde, an extended protein release and preserved enzymatic activity of TGM for up to 30 days were observed.

Impactos do amido resistente e da enzima transglutaminase nas características tecnológicas de espaguete

O uso de amido resistente em novos produtos vem aumentando devido aos benefícios à saúde associado ao consumo de fibras. Entretanto, sua utilização em produtos, como massas alimentícias, é limitada por enfraquecer a rede de glúten. Uma possibilidade para solucionar este problema é a adição da enzima transglutaminase. O objetivo deste estudo foi avaliar a influência da adição de amido resistente (AR) e de transglutaminase (TG) nas características de cozimento, textura, cor e na solubilidade de proteínas de espaguete, através de um delineamento composto central rotacional de duas variáveis independentes (x1 = AR, 0 a 20 %; x2 = TG, 0,2 a 1,0 %). As principais variáveis dependentes estudadas foram: amido resistente, cor instrumental, características de cozimento e de textura e solubilidade de proteínas. Através da Metodologia de Superfície de Resposta analisou-se os resultados que demonstraram que AR e TG apresentaram influência na qualidade dos produtos, sendo estatisticamente significativas (p&lt;0,10) para cor, tempo ótimo de cozimento, aumento de peso, aumento de volume, elasticidade e teor de amido resistente. A luminosidade (L*) foi maior com o aumento de AR e TG. Maiores teores de AR diminuem o tempo de cozimento e a elasticidade. Dentre as variáveis independentes, AR apresentou maior efeito sobre as variáveis dependentes estudadas. O ponto otimizado (0,70 de desejabilidade) necessita do uso de 18,65 % de amido resistente, resultando em um espaguete com apelo de fonte de fibra alimentar, pois contêm mais de 2,5 g de fibra alimentar, por porção, no produto pronto para o consumo.

Thermomechanical behaviors and protein polymerization in bread dough modified by bran components and transglutaminase

The effects of bran components such as cellulose, arabinoxylan (AX), and ferulic acid (FA), and transglutaminase (TG) on the thermomechanical attributes and protein polymerization of bread dough were investigated. Bran components prolonged development time and decreased dough stability, while TG increased the two attributes mainly attributed to its cross-linking ability on gluten proteins. Both AX and TG decreased the setback and hot-gel stability, probably because of the interaction with starch chains that restricted the recrystallization and amylose exudation. Cellulose and AX reduced the elastic and viscous moduli of bread dough, and AX induced more reductions than cellulose. AX fortified with FA caused more water transition from the bound state to the free state than cellulose and AX. TG enhanced the water availability to gluten and resulted in a strengthened gluten network. Briefly, AX exerted more interference with gluten development due to the chain structures and higher water binding ability. TG improved dough strength, but its function could be interfered with by bran components. The study interpreted the interactions between bran components, TG, and gluten protein in bread dough and provided an important experimental basis for the development of bran-containing products.

The influence of the addition of transglutaminase at different phase on the film and film forming characteristics of whey protein concentrate-carboxymethyl chitosan composite films

Abstract To reveal how transglutaminase (TG) affects the forming characteristics of whey protein concentrate (WPC)-carboxymethyl chitosan (CMCS) composite films and to develop the optimum approach for TG-modifying WPC-CMCS composite films, TG was added at different phases to WPC-CMCS composite films, and the properties and structural characteristics of the composite films and their film-forming solutions were investigated. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) results confirmed that TG could promote protein intermolecular polymerization to form macromolecular substances. TG could improve the mechanical and rheological properties of WPC-CMCS composite films, which depended on the TG addition phase during film preparation. The results from the film characterization showed that the mechanical properties and rheological property of WPC-TG-CMCS films are better than those of WPC-CMCS-TG films, which indicated that TG had stronger cross-linking ability with whey protein in WPC-TG-CMCS films. FTIR analysis showed that TG caused conformational changes in whey protein in composite films. X-ray diffraction analysis suggested that TG could promote the polymerization of protein molecules and reduce the porosity of the protein network structure, thus improving crystallinity. All the results suggested that the suitable addition phase of TG had a positive effect on the film-forming characteristics of WPC-CMCS composite films, and the films can be applied as an alternative for some petroleum-based packaging materials.

Roles of selenoprotein T and transglutaminase in active immunization against entomopathogenic fungi in the termite Reticulitermes chinensis

Active immunization can protect individuals from infectious diseases in social insects. It is well established that trace elements are essential to the host immune system, but the related gene functions in insect social immunity are unknown. Here, we found that the levels of three free elements (Se, Ca and Cr) and selenoprotein T (SELT) expression were significantly decreased in the termite Reticulitermes chinensis Snyder during active immunization against the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin. Thus, we further explored the role of the SELT gene in the active immunization of termites. After SELT was significantly silenced by RNAi, the nestmates of fungus-contaminated termites exhibited reduced antifungal activity and increased mortality, along with increased expression of the immune genes transglutaminase (TG) and transferrin (Tsf), indicating that the active immunization of termites was disrupted by SELT silencing. Moreover, the TG-knockdown nestmates of fungus-contaminated termites significantly decreased grooming behavior, antifungal activity and survival, despite the upregulation of SELT expression, also suggesting that the active immunization of termites was disrupted by the silencing of TG. These findings demonstrated that both SELT gene and TG gene play important roles in driving active immunization against the entomopathogenic fungus M. anisopliae in R. chinensis.