Evaluation of Cytotoxicity, Genotoxicity and Hematotoxicity of the Recombinant Spore-Crystal Complexes Cry1Ia, Cry10Aa and Cry1Ba6 from Bacillus thuringiensis in Swiss Mice

Abstract

The insecticidal properties of Cry-endotoxins from Bacillus thuringiensis (Bt) have long been used as spore-crystals in commercial spray formulations for insect control. Recently, some Bt-endotoxin genes have been cloned in many different plants. Toxicological evaluations of three spore-crystal endotoxins, BtCry1Ia, BtCry10Aa and BtCry1Ba6 from B. thuringiensis, were carried out on mice to understand their adverse effects on hematological systems and on genetic material. These three spore-crystals have shown toxic activity to the boll weevil, which is one of the most aggressive pests of the cotton crop. Cry1Ia, Cry10Aa and Cry1Ba6 did not increase the micronucleus frequency in the peripheral erythrocytes of mice and did not cause changes in the frequency of polychromatic erythrocytes. However, some hematologic disburbances were observed, specifically related to Cry1Ia and Cry1Ba6, respectively, for the erythroid and lymphoid lineage. Thus, although the profile of such adverse side effects can be related to their high level of exposure, which is not commonly found in the environment, results showed that these Bt spore-crystals were not harmless to mice, indicating that each spore-crystal endotoxin presents a characteristic profile of toxicity and might be investigated individually.

Toxicological Evaluation of a Potential Immunosensitizer for Use as a Mucosal Adjuvant—Bacillus thuringiensis Cry1Ac Spore-Crystals: A Possible Inverse Agonist that Deserves Further Investigation

“…So, because there have been no reports of known receptors in the gut cells of the vertebrates and the physiology of their digestive system, δ-endotoxins have been considered as presenting inconsiderable toxicity to humans and other mammals [ 25 , 26 ]. However, the literature addressing the biosafety of δ-endotoxins for non-target organisms is scarce, and our present and previous works [ 19 , 21 ] have demonstrated hematotoxicity mainly for the erythroid lineage of mice after a single oral administration, corroborating another study demonstrating in vitro hemolysis in cell lines of rat, mouse, sheep, horse, and human erythrocytes [ 27 ]. This data suggests that the plasma membrane of erythrocytes could be the primary target for these toxins [ 19 , 27 ], and that Cry toxins are not completely destroyed in the stomach, having their toxic form activated by intestinal alkaline pH.…”

“…Therefore, the applicability of Cry1Ac proteins as potential tools in combating diseases in humans and other mammals further highlights the importance of studies directed to the biosafety of non-target organisms. This is mainly because although Cry toxins have been considered harmless to humans and other vertebrates [ 2 , 18 ], studies by our group have demonstrated that Bt spore-crystals caused hematologic disturbances for the erythroid and lymphoid lineages of Swiss mice [ 19 , 20 , 21 ], indicating that each spore-crystal endotoxin presents a characteristic profile of toxicity and might be investigated individually [ 21 ].…”

Possible health impacts of Bt toxins and residues from spraying with complementary herbicides in genetically engineered soybeans and risk assessment as performed by the European Food Safety Authority EFSA

“…As far as potential effects on health are concerned, several authors [38–43] show that Cry proteins could potentially have an impact on the health of mammals. Also de Souza Freire et al [44] confirm haematoxicity of several Cry toxins. Some of these effects seem to occur where there are high concentrations and tend to become stronger after several days.…”

Co-delivery of cisplatin and paclitaxel by folic acid conjugated amphiphilic PEG-PLGA copolymer nanoparticles for the treatment of non-small lung cancer

“…The concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), serum creatinine (Scr), and blood urea nitrogen (BUN) were calculated with the use of a Biochemical Auto-analyzer (7170S, Hitachi, Japan). [ 30 , 31 ]…”