Alteration of blood brain barrier permeability by T-2 toxin: Role of MMP-9 and inflammatory cytokines.
T-2 toxin is a cytotoxic fungal secondary metabolite produced by different species of Fusarium such as F. sporotichioides, F. poae, F. equiseti, F. acuminatum etc. This class of mycotoxins causes a number of pathologies including nervous disorders, cardiovascular alterations, immunodepression and hemostatic derangements. In the present study, mechanism of T-2 toxin induced alteration of blood-brain barrier (BBB) permeability was assessed in terms of oxidative stress, gene expression of MMP-9, MMP-2 and their inhibitors TIMP-1 and TIMP-2, activation of inflammatory cytokines in both brain and peripheral tissue spleen. Gel zymography was used to show the activity of MMP-9 and MMP-2. The percutaneous exposure of 1 LD50 T2 toxin caused a reversible alteration in BBB permeability as observed by extravasation of Evans blue dye. Maximum dye level was observed on day 3 and reduced by day 7. A significant GSH depletion was observed on days 1 and 3. Brain ROS and lipid peroxidation levels increased significantly on 1 and 3 days and decreased by day 7. The SOD levels in brain showed significantly higher activity on 3 days (4-fold) and 7 days (5-fold) of toxin exposure compared to control. A similar trend was observed with catalase enzyme levels. The gene expression analysis of cNOS and iNOS showed varying levels of expression on different time points of post exposure. MMP-9 expression was significantly high on days 3 and 7 in brain with corresponding alteration in TIMP-1. MMP-2 and TIMP-2 showed no effect. Gene expression analysis of the inflammatory cytokines, IL-1α, IL-1β, IL-6 and TNF-α showed elevated levels on day 7 in brain. As spleen plays an important role in inflammatory response we analyzed MMP-9, MMP-2 and inflammatory cytokines in spleen. The MMP-9 was activated on day 7. MMP-2 activity was found to be elevated on 3 and 7 days and TIMP-2 mRNA level increased on 1 and 3 days in spleen. Inflammatory cytokines, IL-1 α, IL-1β, IL-6 and TNF-α showed elevated levels on days 1 and 3 in spleen indicating an early effect in spleen than in brain. In summary, the results of the study showed that the T-2 induced alteration in BBB permeability is mediated through oxidative stress, activation of MMP-9, and proinflammatory cytokines in brain as well as contribution from peripheral tissue spleen.
Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Jhansi Road, Gwalior 474002, India.
Jayaraj
J
Ravindran
Mona
M
Agrawal
Nimesh
N
Gupta
P V Lakshmana
PV
Rao
D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000502:physiology*; D007249:Inflammation / Q000276:immunology*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000502:physiology*; D051379:Mice; D052247:Nitric Oxide Synthase Type II / Q000032:analysis; D018384:Oxidative Stress; D010539:Permeability; D013154:Spleen / Q000187:drug effects / Q000276:immunology; D013605:T-2 Toxin / Q000633:toxicity*
D016207:Cytokines; D052247:Nitric Oxide Synthase Type II; D020780:Matrix Metalloproteinase 9; D013605:T-2 Toxin